How the structure of cartilage tissue determines its function. Cartilage tissue: what is it, cartilage cells, types, structure, functions

All our bones in the process of embryonic (embryonic) development are formed from cartilage. In an adult, they make up no more than 2% of body weight. Bones grow thanks to the diaphyseal cartilage, they lengthen until the so-called growth zones are closed1. However, some of them increase throughout a person's life. It has been established that the lower jaw, nose, ears, feet and hands are constantly growing, albeit at a slow pace.

Most often, athletes leave sports due to injuries of the articular-ligamentous apparatus. Its weak point is cartilage. Spinal problems are also mainly due to the pathology of the intervertebral cartilage.
We can say that in sports traumatology, cartilage treatment is the No. 1 concern. However, some authors believe that they are restored by no more than 50%, thus calling into question the possibility of complete restoration of sports performance. Let's try to consider in more detail what cartilage is and determine the limits and methods of its regeneration.

Cartilage is one of the types of connective tissue that performs supporting functions in the body. An indispensable attribute of cartilage, with the exception of the articular, is the perichondrium, which provides its nutrition and growth. In the joints, the cartilage is exposed and is in direct contact with the internal environment of the joint - the synovial fluid. It acts as a kind of lubricant between the rubbing surfaces of the joints, covered with smooth gliain cartilage. The cartilage of the bones and spine is constantly undergoing both static and dynamic loads. The cartilages of the nose, larynx, bronchi, fibrous triangles in the heart also carry out a supporting function.

The structure of the cartilage allows it to experience reversible deformation and at the same time maintain the ability to metabolize and reproduce. Its main components are cartilage cells (hendrocytes) and an extracellular matrix, consisting of fibers and a basic substance. Moreover, most of the mass of cartilage is precisely the intercellular substance.
Depending on the predominance of collagen, elastic fibers or the main substance, hyaline, elastic and fibrous cartilage are distinguished.

A feature of cartilage, in comparison with other types of tissues in the body, is that there are few cells in it and they are surrounded by a large amount of intercellular space - the matrix. Cartilage recovers so poorly after damage precisely because there are very few cells that can multiply and the main part of the repair (recovery) is due to the extracellular matrix. Elastic cartilage (larynx, nose, auricle) contains a lot of elastin (for example, 30% of the human ear consists of it).

There is a lot of water in the articular cartilage (in the cartilage of the head of the femur of a young man - 75 g per 100 g of tissue). Glauronic acid helps the matrix to bind water, which provides the elastic and elastic properties of the tissue.
In hyaline cartilage, which most often represents the intra-articular surface, half of the entire matrix is \u200b\u200bcollagen, the main protein of connective tissue. Only the tendons and dermis (the deep layer of the skin) surpass the matrix in terms of collagen saturation. Its greatest concentration in the articular cartilage is concentrated in the superficial zone.
Collagen is a collective concept; there are several types of it. Different in chemical composition, they all, however, consist of very large molecules coiled into triple helices. This structure of the fibers makes them very resistant to twisting, stretching and tearing. Each of the three chains has a polypeptide structure.
If we analyze the composition of the polypeptide chains of any of the three types of collagen (there are exactly three of them in humans), we will see that the highest specific gravity of the amino acid glycine. It is followed by the amino acids promene (proline -?) And alanine in terms of specific gravity. Sometimes alanine "outweighs" proline, and sometimes on the contrary, proline surpasses alanine in its specific gravity.

Elastic cartilage (for example, of the nose and ears) contains predominantly elastin in its matrix, which, like collagen, forms strong fibers. They are thinner than collagen, but are very durable. Tissues containing a large amount of elastin are capable of very large reversible deformations. The main amino acid of elastin (as well as collagen) is glycine. It is followed by alanine, proline and valine in percentage terms.
Elastin, like collagen, is of several types. Elastin fibers also have a peptide character and a spiral shape. This explains their great extensibility. The spiral, however, is not triple, but single, so elastin fibers are thinner than collagen fibers. In different cartilages, either collagen or elastin fibers predominate in the matrix. They are all intertwined in a solid three-dimensional web. The collagen (elastin) network "holds" other molecules inside the cartilage, both mechanically and electrostatically.

The biomechanical properties of cartilage make them highly specific and essentially unique components of the musculoskeletal system.
They:
a) take on the action of external mechanical forces of compression and tension; distribute these forces evenly, absorb and dissipate them, translating axially directed forces into tangential ones (in the joints of the limbs, spine, etc.);
b) form wear-resistant surfaces of the joints of the skeleton, participate in the formation of the lubricating apparatus in the synovial joints;
c) are the place of attachment and support for soft tissues and muscles; form cavities in places of contact with the external environment (cartilage of the nose, ears, respiratory organs).

The cartilage matrix is \u200b\u200bbelieved to be composed of 3 main components:
1) a fibrous collagen framework that forms a three-dimensional network of weaves;
2) molecules of proteoglycans, which fill the loops of the fibrous cage;
3) water freely moving between the framework weaves and proteoglycan molecules.

Articular cartilage does not have blood vessels. It feeds diffusely, absorbing nutrients from the synovial fluid.

The collagen scaffold is like the "skeleton" of the cartilage. It is highly elastic in relation to tensile forces and at the same time has relatively little resistance to compressive stress. Therefore, intra-articular cartilages (for example: menisci and articular surfaces of the femur and tibia) are easily damaged under compression (compressive) loads and almost never under tensile loads ("tear").
The proteoglycan component of the matrix is \u200b\u200bresponsible for the cartilage's ability to bind water. It can be removed outside the cartilage into the synovial fluid and back into it. It is water as an incompressible substance that ensures sufficient rigidity of the cartilage. Its movement evenly distributes the external load throughout the cartilage, as a result of which external loads are weakened and the deformations arising under loads are reversible.

The elastic cartilages of the larynx and trachea contain a very small number of vessels. Collagen cartilage of the joints does not contain any vessels at all. A large mechanical load on the cartilage is incompatible with vascularization (vascular supply). The exchange in such cartilage is carried out due to the movement of water between the components of the matrix. It contains all the metabolites necessary for cartilage. Therefore, both anabolic and catabolic processes are sharply slowed down in them. Hence their poor post-traumatic recovery, in contrast to cartilage with vascularization.
In addition to gliainic and elastic cartilage, another group is distinguished - fibrous, or fibrous cartilage. Fibrosis means fiber. The matrix of fibrous cartilage is formed by collagen fibers, however, in comparison with, say, gliain cartilage, the bundles of collagen fibers are thicker and do not have a three-dimensional weave structure. They are oriented mainly parallel to each other. Their direction corresponds to the vectors of tension and pressure forces. Intervertebral discs are made of fibrous cartilage, which are highly durable. Large collagen fibers and their bundles are located in the intervertebral discs circularly. In addition to the intervertebral discs, fibrous cartilage is found in the places where tendons attach to bones or cartilage, as well as in the joint of the pubic bones.
The maintenance of the entire structural integrity of the cartilage matrix depends entirely on chondrocytes. And although their mass is small, they nevertheless synthesize all the biopolymers that make up the matrix - collagen, elastin, proteoglycons, glycoproteins, etc. With a specific gravity of 1 to 10% of the total volume of cartilage tissue, chondrocytes provide the formation of large masses of the matrix. They also control all catabolic reactions in the cartilage.

What is the reason for the low metabolic activity of cartilage? Only in one - in a small number of cells (1-10%) per unit volume of tissue. In terms of net cell mass, the metabolic rate of chondrocytes is no less than that of other cells in the body. The articular cartilage and pulp nuclei of the intervertebral discs are especially low in metabolism. It is these structures that are distinguished by the smallest number of chondrocytes (1% of the total mass of cartilage) and they are the ones that recover from damage the worst of all.

Oxidative processes in cartilage proceed mainly by anaerobic (anoxic) pathway. So, for example, the chondrocytes of the nucleus pulposus of the intervertebral discs feed 99% anaerobically and only 1% aerobically. On average, oxygen oxidation in cartilaginous tissue is at least 50 times less intense than in ordinary body tissues. The anaerobic nature of oxidation in chondrocytes is a protective and adaptive reaction that has developed in the process of evolution. And this is not surprising, considering that the cartilage has no (glacial, fibrous) or almost no (elastic) blood supply. If we start introducing oxygen into the space bordering with the cartilage, then diffusion into the cartilage of O2 not only does not improve its trophism, but, on the contrary, sharply worsens it.

How low the metabolic activity of the cartilage is can be understood from the following comparison. The protein composition of the liver is completely renewed in 4 (!) Days. Cartilage collagen is renewed by only 50% in 10 (!) Years. Therefore, it becomes clear that any injury to cartilage tissue is practically incurable, unless special measures are taken to increase the number of chondrocytes that will form a new matrix.

Regeneration of cartilaginous tissue, both physiological and reparative (restorative), directly depends on the hormonal background and the modulating effect of certain hormones. For example, glucocorticoid hormones inhibit anabolic reactions in chondrocytes, inhibit the synthesis of collagen and proteoglycans, and cause a deficiency of gluronic acid in the synovial fluid and in the matrix. And this inhibitory effect of glucocorticoids is more pronounced if it is combined with compression (compression) of the cartilage. In principle, this is not surprising, given that glucocorticoids inhibit glycolysis - the anaerobic oxidation of glucose in cartilage. Regeneration without energy supply becomes simply impossible. Insulin stimulates collagen synthesis in the matrix of cartilage tissue, but this stimulation is small and mediated.

The strongest factor that stimulates both physiological and reparative synthesis in cartilaginous tissue is growth hormone. The affinity of cartilage for growth hormone is absent as such. However, under the action of somatotropic hormone, insulin-like growth factor (IGF-1) is formed in the liver, which has its own anabolic effect on all tissues, including cartilage. Growth hormone itself is capable of exerting an anabolic effect on cells only if its concentration is 2000 times higher than physiological. This is possible only in a test tube and is completely excluded in real life. When using somatotropin for a reparative purpose, it must be remembered that its effect on the synthesis of IGF-1 is possible only under conditions of normal liver function, in the absence of serious diseases, otherwise IGF-1 will simply not be synthesized and the introduction of somatotropin will not give any result. The ability of somatomedin to enhance the regeneration of cartilage tissue is 100 times higher than the effect of the introduction of insulin and testosterone into the body. IRF-1 is the only factor that causes division (multiplication) of chondrocytes. Other anabolic factors of the body (and there are quite a few of them) do not have this ability.

Thyroid hormones can enhance the recovery and physiological growth of cartilage when used in small amounts close to physiological. Then they have an anabolic effect on all tissues of the body. In medium to large amounts, thyroid hormones have an even greater anabolic effect, however, at the same time they cause an energy deficit (thermogenic effect) and increased catabolism.
In this case, catabolism increases to a greater extent than anabolism and the activity of destructive processes exceeds the synthetic activity. No matter how anabolism increases with increasing doses of thyrsoid hormones, catabolism increases even more and this must be remembered.
Thyrocalcitonin is the only thyroid hormone that enhances the restoration and growth of cartilaginous tissue in any amount, but for this it must be used in isolation, separately from thyroxine and triedironine - the "main" thyroid hormones.
The parathyroid hormone (parathyroid hormone) has a moderately stimulating effect on cartilage regeneration.

Testosterone - the main androgen of the body moderately stimulates biosynthetic processes in cartilage, and estrogens - female sex hormones, on the contrary, inhibit it.
Anabolic steroids have the ability to induce cartilage regeneration to a much greater extent than pure testosterone, and this is not surprising when you consider that they have an anabolic effect several times higher than the anabolic effect of testosterone.

It is interesting that the matrix - the product of chondrocytes - lives its own independent life. It is able to modulate the action of various hormones on chondrocytes, weakening or enhancing their action. By acting on the matrix, you can change the state of chondrocytes both for the better and for the worse. Removal of a part of the matrix causes an immediate intensification of the biosynthesis of the macromolecules missing in it. Moreover, the proliferation (proliferation) of chondrocytes simultaneously increases. Quantitative changes in the matrix can cause their qualitative changes.
Prolonged limitation of movement in the joint (plaster immobilization, etc.) leads to a decrease in the mass of cartilage. The reason is surprisingly simple: there is no mixing of synovial fluid in a motionless joint. In this case, the diffusion of molecules into the cartilage tissue slows down and the nutrition of chondrocytes deteriorates. The lack of direct compressive load (compression) also leads to a deterioration in the nutrition of chondrocytes. Cartilage needs at least a minimal compression load to maintain normal trophism. Excessive tensile stress in the experiment causes the degeneration of the cartilage with the development of coarse fibrous fibers.

The synovial membrane has a very complex effect on the state of the intra-articular cartilage. It can both enhance the anabolism of the cartilage tissue and enhance its catabolism. Removal of the synovium sharply worsens the trophism of the cartilage, which is restored only after its regrowth.
Chondrocytes are also capable of autoregulation. They synthesize special growth factors that stimulate the proliferation of neighboring chondrocytes. Until their structure is fully deciphered. It is only known that they are of a polypeptide nature.

All cartilage, but especially the cartilage of the musculoskeletal system, is constantly exposed to microtraumatization. This primarily applies to the intervertebral discs, the most vulnerable part of which is the nucleus pulposus. Already in adolescence (starting from the age of 16), dystrophic changes begin in the intervertebral discs of the cervical spine. In terms of unit of cross-section, it carries a load much greater than any other part of the spine, including the lumbar. First of all, dystrophic changes concern the nucleus pulposus. Some of its cells die and are replaced by coarse connective tissue. Similar, but less pronounced changes occur in the intervertebral disc itself. In places, focal growth of chondrocytes occurs. The body seeks to repair damaged cartilage and starts reparative processes. However, in places of death of chondrocytes, there is a coarse-fibrous connective tissue - a kind of scar. And just in it, where they are needed, chondrocytes cannot recover. Their growth occurs along the periphery of the scar tissue, where they are actually not needed. This leads to unnecessary deformation of the cartilage, which further impairs its function. The main function of cartilage is supporting and stabilizing. With the development of degenerative and dystrophic processes in the intervertebral discs, the vertebrae lose stability and gradually become hypermobile, easily displaceable. Their hypermobility can cause compression of the surrounding soft tissues. Edema of soft tissues, in turn, causes compression of the vessels and nerves passing through them, with the development of corresponding symptoms. The body seeks to restore the stability of the articular-ligamentous apparatus. There is a proliferation of individual sections of the vertebrae in the form of a kind of bone outgrowths - "whiskers". These "whiskers" squeeze nearby soft tissues, causing them to swell and secondary compression of nearby vessels and nerves. The whole complex of changes in the osteochondral apparatus in this case is called osteochondrosis, although this term is very vague, unspecified, and, in fact, not very scientific.

If negative phenomena develop in the cervical spine from adolescence, then in the lumbar spine, where the load per unit of cross-section is much lower - starting from 25-30 years. In general, they are of the same morphological nature as in the cervical spine, but differ in clinical (medical) signs. In the cervical spine, large arteries pass through the transverse processes of the cervical vertebrae, supplying the entire base of the brain and its stem part, where the vital centers (respiration, blood circulation, etc.) are located. With the development of cervical osteochondrosis, there is a gradual imperceptible compression of these arteries with the development of cerebral circulation insufficiency. In this case, there are practically no (or they are very rare) any painful signs of the process. In the lumbar spine, the picture is somewhat different. Nerve roots that carry sensory fibers from the lower extremities and motor fibers to the muscles of the legs emerge from this section. Lumbar osteochondrosis is primarily manifested by various pain symptoms, impaired sensitivity and motor sphere. At the same time, it does not violate any vital functions of the body. Cervical osteochondrosis does not reveal itself with any painful signs and does not cause any particular inconvenience, however, it can lead to serious disorders of cerebral circulation, up to strokes with the development of paralysis.

Cervical osteochondrosis manifests itself in a variety of symptoms that can simulate other diseases. Deterioration of cerebral circulation is manifested by a decrease in working capacity, rapid fatigue, and headache. Eye fatigue, flies before the eyes, a feeling of "sand in the eyes" are characteristic signs of cervical osteochondrosis. Ringing in the ears and hearing impairment are more likely to indicate cerebral circulation disorders due to osteochondrosis than diseases of the hearing system. According to the latest data, 85% of all brain hemorrhages at a later age are caused not by age-related arterial pathology as such, but by compression of the cervical arteries as a result of widespread cervical osteochondrosis.

Age-related changes in elastic cartilage are not fatal. They are expressed mainly in ossification - the accumulation of calcium and do not lead to any noticeable dysfunction.
In the gliamine cartilage of the joints, fibrillation is found already starting from the age of 30 - the disruption of the cartilaginous surface. Microscopic examination reveals breaks and splits on the surface of the cartilage. Cartilage splitting occurs both vertically and horizontally. In this case, in some places there are an accumulation of cells of cartilage tissue as a response of the body to the destruction of cartilage. Sometimes there is an age-related increase (!) In the thickness of articular cartilage as a response to the action of mechanical (training) factors. The age-related evolution of the cartilage of the knee joint has been noted by many researchers since the age of 40. The most significant change observed with aging cartilage is a decrease in water content, which automatically leads to a decrease in its strength.

Hence the extreme complexity of his post-traumatic treatment. Moreover, sometimes it is not easy even to maintain the normal state of the cartilage during the normal training process. The growth of muscle tissue is ahead of the strengthening of the articular-ligamentous apparatus and, in particular, its cartilaginous part. Therefore, sooner or later, the loads reach such a value that the cartilaginous part of the musculoskeletal system can no longer withstand. As a result, there are “inevitable” hard-to-heal injuries, due to which the athlete sometimes leaves sports. Self-repairing cartilage is never complete. In the best case, the cartilage is restored by 50% of its original value. However, this does not mean that its further restoration is impossible. It is possible with competent pharmacological action, designed to cause, on the one hand, the multiplication of chondrocytes, and on the other, a change in the state of the cartilage matrix. The problem of cartilage restoration is greatly complicated by the fact that scar tissue develops in place of the dead cartilage tissue. It prevents the cartilage from regenerating in the right place. Compensatory growth of cartilage areas in the vicinity of the injury site leads to its deformation, complicating the task of pharmacological growth stimulation. However, all these difficulties are surmountable if the deformed cartilage is first subjected to surgical correction.

The potential for cartilage regeneration is great. It can regenerate due to its own potential (reproduction of chondrocytes and growth of the matrix) and, equally important, due to other types of connective tissue that have a common origin with it. Tissues adjacent to cartilage have the ability to reorient their cells and turn them into cartilage-like tissue, which does a good job with its functions. Take, for example, the most common type of injury - intra-articular cartilage injury.

The source of regeneration are:
1) the cartilage itself;
2) the synovial membrane of the joint, growing from the edges of the defect and turning into cartilage-like tissue;
3) bone cells, which, let's not forget, are of cartilaginous origin and, if necessary, can be transformed "back" into tissue resembling cartilaginous in structure;
4) bone marrow cells, which can serve as a source of regeneration in case of deep damage to the cartilage in combination with bone damage.

Immediately after the injury, an “explosion” of mitotic activity of chondrocytes is observed, which multiply and form a new matrix. This process is observed within 2 weeks after damage, however, the remodeling of the cartilage surface lasts at least 6 months, and completely stops only after a year. The quality of the "new" cartilage is, of course, inferior to the quality of the "old". If, for example, hyaline intra-articular cartilage is damaged, then after 3-6 months a regenerate grows that has the character of hyaline-fibrous young cartilage, and after 8-12 months, it already turns into a typical fibrous cartilage with a matrix consisting of tightly adjacent collagen fibers.
All researchers of the cartilage tissue are unanimous in one thing: the cartilage is not able to restore the lost only due to its own internal resources and mechanisms. They are enough for a maximum of 50% of the regenerate. Some more growth of the regenerate is carried out at the expense of other types of connective tissue, which we have already discussed, but there is still no need to talk about complete 100% restoration of cartilage. All this brings a fair amount of pessimism to the assessment of the possibility of recovery after some serious injury to the cartilage, but there are still reasons for optimism. Achievements of pharmacology and transplantology today are such that we can talk about full compensation of even very serious cartilage defects, no matter how laborious it is.

The completeness of the restoration of damaged cartilaginous tissue largely depends on the quality of the post-traumatic period, when the hematoma is just forming1. Then it is impregnated with a special kind of protein - fibrin, sweating from the blood plasma, and turns into scar tissue. And she, as we know, is a serious obstacle to the development of a full-fledged regenerate in this place. Therefore, immediately after injury, it is necessary to take all possible measures to prevent the development of hematoma and soft tissue edema. Cool the injured area. To do this, it is covered with ice, irrigated with chloroethylene. If the joint of the limb is damaged, then it can simply be placed under a stream of cold water. Timely assistance from a qualified trauma doctor is very important. Local novocaine blockades not only anesthetize the injured area, but also prevent the development of edema and inflammation. The blockade can be repeated until the acute period has passed. If, as a result of a bruised joint, a hemorrhage occurs in its cavity - hemarthrosis, then it is necessary to pump out blood from the joint as soon as possible. It is not difficult to do this with an ordinary syringe. Sometimes it is necessary to pump out blood and transudate (fluid that sweats into the joint cavity from blood plasma) several times in a row. In no case should you wait for the blood to “dissolve by itself”. A blood clot as a result of the loss of a special kind of protein - fibrin, a large amount of scar tissue can develop. The damaged joint may remain deformed and enlarged. A sad example is the "kentus" of those who practice karate. Broken finger joints increase in size due to hemorrhages and so remain enlarged due to the fact that blood is not pumped out of them in time. Despite the frightening appearance, fists with broken joints are much weaker than normal ones and are very easily damaged by repeated injury.

In the subacute period, when soft tissue edema and pain syndrome are significantly reduced, care must be taken to dissolve the damaged tissue as completely as possible. For this purpose, he uses proteolytic enzymes (trypsin, cheleotrypsin, papain, etc.), which are introduced into the damaged area using electrophoresis. A good effect is given by glucocorticoid hormones - hydrocortisone, prednisolone, etc. Like proteolytic enzymes, they are injected locally, into the affected area - be it the intervertebral disc or the joints of the extremities. Hydrocortisone is given by ultrasound and prednisolone is given by electrophoresis. Sometimes glucocorticoid hormones are injected into the joint cavity, for example, in the treatment of knee injuries. He has the most complex structure and it is very difficult to treat his injuries. Menisci - intra-articular cartilage in the knee joints practically does not grow together with damage. Therefore, if there are tears or tears of parts of the menisci, they must be removed as soon as possible. It is easier to "grow" a regenerate at the site of a removed meniscus (and such a regenerate must grow) than to achieve healing of a damaged meniscus. Fortunately, in recent years, arthroscopy has developed widely and knee surgery is becoming more and more gentle. The arthroscope allows using fiber optics to look inside the joint without opening it (only a few holes are made). Surgical intervention is also performed through the arthroscope. Sometimes it happens that as a result of injury, the meniscus remains intact, but breaks off from the place of its attachment. If earlier such a meniscus was always removed, now more and more specialists appear who sew the torn off meniscus into place. After freshening the edges of the wound, the sewn meniscus grows into place.

If arthroscopy reveals the razvlecheniya of certain cartilaginous surfaces, then they are polished, "bite" with special nippers fibers and areas of deformed cartilage. If this is not done, then the subsequent measures taken to enhance the regeneration of cartilaginous tissue can lead to the growth of deformed cartilage and impairment of its supporting functions.

In case of superficial damage, it is possible to achieve complete restoration of the cartilage by using potent pharmacological agents. Over the past 40 years of experimental and clinical work, only one single drug has proven its high efficiency - growth hormone (STH). It stimulates the growth of cartilage tissue 100 times more than the administration of testosterone and insulin. An even greater effect is exerted by the combined administration of STH and thyrocalcitonin, a special kind of thyroid hormone that enhances the repair of both bone and cartilage tissue. The exceptional effectiveness of STH on cartilage repair is due to the fact that it directly stimulates the division of chondrocytes. Using STH, it is theoretically possible to bring the number of chondrocytes to any desired amount. They, in turn, restore the matrix to the required volume, synthesizing all its components, starting with collagen fibers and ending with proteoglycans. The disadvantage of STH is that it cannot be applied topically, injecting directly into the affected area of \u200b\u200bcartilage tissue, since it acts indirectly. Growth hormone causes the formation of insulin-like growth factor (IGF-1) in the liver, which has a strong anabolic effect. Its parenteral (injection) administration causes the growth of not only damaged cartilage, but also normal cartilage, which is undesirable, because there are bones in the body in which the cartilaginous growth zones do not close throughout life. Prolonged administration of large doses of STH into a formed organism can cause skeletal imbalances. Although it should be noted that it acts more strongly on the affected cartilage, and there are no obvious skeletal deformities in the treatment of STH in the scientific literature.

In recent years, a dosage form of IRF-1 has been synthesized, which is increasingly used by injection instead of somatotropin. Since IRF-1 acts directly on tissue (including cartilage), there is a tempting prospect of using it for local administration (electrophoresis, ultrasound, etc.). Such use of IRF-1 would make it possible to localize its action at the site of the affected cartilage and exclude the effect on healthy cartilage of the body.
Anabolic steroids (AS) have a good effect on the restoration of cartilage and the surrounding connective tissue. In terms of efficiency, they are in second place after IRF-1 and growth hormone, although they do not directly cause division of chondrocytes. Anabolic steroids, however, accelerate physiological regeneration and potentiate the anabolic action of insulin and other endogenous anabolic factors, blocking the action of catabolic hormones (glucocorticoids). The practical application of AS in surgical and trauma practice has proven their high efficiency. It is a pity that dosage forms of the AU for local use have not yet been developed. This would make it possible to create high concentrations of the medicinal substance precisely at the site of injury and prevent systemic (at the level of the whole organism) side effects. Unfortunately, research in this area is not funded by anyone due to the classification of the AU as a doping agent in sports.

Some researchers in the field of molecular biology have presented very convincing material proving that stimulants (2-adrenergic receptors are able to simulate the anabolic effects of somatomedins and, in particular, in relation to cartilage tissue. The mechanism of this action is not entirely clear. It is possible that it simply increases sensitivity liver to endogenous somatotropic hormone and the synthesis of IGF-1 in the liver increases. One of the most powerful selective stimulants (2-adrenergic receptors is clenbuterol. This drug does not have hormonal effects and, at the same time, has a good anabolic effect. Like IGF-1) it stimulates the growth of cartilaginous tissue and can be successfully used in the post-traumatic recovery period.Drugs that stimulate (there are many 2-adrenergic receptors, but I would especially like to mention such an old and proven remedy as adrenaline. Adrenaline is a hormone of the adrenal medulla even with a long course of use ai is not addictive. In large doses, adrenaline acts mainly on the α-adrenergic receptors. There is a narrowing of the vessels of the skin, an increase in blood pressure, an increase in blood sugar levels. Small doses of adrenaline do not affect α-adrenergic receptors, stimulate (2-adrenergic receptors. Muscle vessels dilate, blood sugar and blood pressure decrease. A general anabolic effect develops, and especially in relation to cartilage tissue. Daily administration of small (precisely small!) doses of adrenaline has proven itself well as a means of promoting regeneration.

Some vitamins in large pharmacological dosages can significantly increase the release of endogenous growth hormone into the bloodstream. The palm is held by nicotinic acid (vitamin PP). Intravenous administration of relatively small doses of nicotinic acid can increase the basal secretion of GH by 2-3 times. Increases the secretion of growth hormone vitamin K, only it must be used in moderate doses so as not to increase excessive blood clotting.

Despite the fact that the matrix of cartilage tissue is a derivative of chondrocytes, changing its state can improve their activity. The state of the matrix can be improved by using large doses of ascorbic acid in combination with vitamin P. Ascorbic acid has a particularly strong effect on the state of collagen structures. Therefore, it is traditionally used to enhance collagen synthesis, especially when combined with glycine and anabolic steroids. A combination of large doses of ascorbic acid with lysine, alanine and proline is also used.
The condition of the cartilage matrix of intra-articular cartilage can be temporarily improved with the help of substances injected into the synovial fluid. In recent years, the introduction of a 15% solution of polyvinylpyrrolidone into the joint has been especially widely used, where it stays for about 5-6 days, then the procedure is repeated, sometimes several times. Polyvinylpyrrolidone serves as a kind of temporary "prosthesis" of intra-articular fluid. It improves the friction of the intra-articular surfaces, temporarily relieving stress on the articular cartilage. In cases of severe, irreversible damage to the cartilage tissue, prosthetics are used, which, as the surgical technique develops, gives more and more encouraging results. Already you will not surprise anyone with intervertebral disc prostheses. Unsuccessful attempts are being made to replace the intra-articular cartilage (meniscus) of the knee joints.
A very promising direction is the introduction of a suspension of chondrocytes into the damaged areas. Weak regeneration of cartilage tissue, as we remember, is due to the small number of cartilage cells (chondrocytes) per unit mass of cartilage tissue. Foreign chondrocytes, being introduced, say, into the joint cavity do not cause a rejection reaction, because have weak immunogenic activity. They are able to multiply and form new cartilage tissue. A suspension of chondrocytes obtained from the cartilage of cattle, deceased people is used. The most promising is the use of embryonic (germ) cartilage cells. They do not cause an immune response at all and, multiplying, cause the formation of new cartilage tissue. Unfortunately, all work with germ cells is still experimental in nature and has not entered into widespread practice. But this is a matter of the near future. The problem of cartilage tissue repair should soon be solved. All the prerequisites are already in place for this.

1 Cessation of the growth of most bones in length can be a sign that treatment is already possible, for example, with anabolic steroids, which lead to premature closure of the growth zone of the cartilage, if the growth zones of the uze are closed (which is evident from an X-ray of the radius of a young person), then there is no longer the danger of closing the growth zones of steroid use too quickly, which means that their use can begin.

1 Literally it means "blood tumor", but the term does not quite correspond to the essence of the phenomenon. A hematoma is diffusely damaged tissue that is swollen with blood.

From Muscle Nutrition Review # 8

Cartilage is a type of connective tissue made up of cartilage cells (chondrocytes) and a large amount of dense intercellular substance. Serves as a support. Chondrocytes have various shapes and lie singly or in groups within the cartilaginous cavities. The intercellular substance contains chondrin fibers, similar in composition to collagen fibers, and the main substance, rich in chondromucoid.

Depending on the structure of the fibrous component of the intercellular substance, three types of cartilage are distinguished: hyaline (vitreous), elastic (mesh) and fibrous (connective tissue).

Cartilage pathology - see Chondritis, Chondrodystrophy.

Cartilage tissue (tela cartilaginea) is a type of connective tissue characterized by the presence of dense intercellular substance. In the latter, a basic amorphous substance is distinguished, which contains compounds of chondroitinsulfuric acid with proteins (chondromucoids) and chondrin fibers, which are similar in composition to collagen fibers. Cartilage fibrils are of the primary fiber type and have a thickness of 100-150 Å. Electron microscopy in the fibers of the cartilage tissue, in contrast to the actual collagen fibers, reveals only an unclear alternation of light and dark areas without a clear periodicity. Cartilage cells (chondrocytes) are located in the cavities of the basic substance singly or in small groups (isogenic groups).

The free surface of the cartilage is covered with dense fibrous connective tissue - the perichondrium, in the inner layer of which there are poorly differentiated cells - chondroblasts. The cartilaginous tissue of the perichondrium does not cover the articular surfaces of the bones. The growth of cartilage tissue is carried out due to the multiplication of chondroblasts, which produce the basic substance and subsequently turn into chondrocytes (appositional growth) and due to the development of a new basic substance around the chondrocytes (interstitial, intussusceptual growth). During regeneration, the development of cartilage tissue can also occur by homogenizing the basic substance of the fibrous connective tissue and converting its fibroblasts into cartilage cells.

Cartilage is nourished by diffusion of substances from the blood vessels of the perichondrium. In the tissue of the articular cartilage, nutrients penetrate from the synovial fluid or from the vessels of the adjacent bone. Nerve fibers are also localized in the perichondrium, from where individual branches of non-fleshy nerve fibers can penetrate into the cartilage tissue.

In embryogenesis, the cartilaginous tissue develops from the mesenchyme (see), between the adjacent elements of which there are layers of the basic substance (Fig. 1). In such a skeletal anlage, hyaline cartilage is first formed, temporarily representing all the main parts of the human skeleton. In the future, this cartilage can be replaced by bone tissue or differentiate into other types of cartilage tissue.

The following types of cartilage tissue are known.

Hyaline cartilage (Fig. 2), from which the cartilage of the respiratory tract, the thoracic ends of the ribs and the articular surfaces of the bones are formed in humans. In a light microscope, its main substance appears to be homogeneous. Cartilage cells or their isogenic groups are surrounded by an oxyphilic capsule. In differentiated areas of cartilage, a basophilic zone adjacent to the capsule and an oxyphilic zone located outside of it are distinguished; Taken together, these zones form the cell territory, or chondrin ball. A complex of chondrocytes with a chondrin ball is usually taken as a functional unit of cartilaginous tissue - a chondron. The main substance between the chondrons is called interterritorial spaces (Fig. 3).

Elastic cartilage (synonym: reticular, elastic) differs from hyaline in the presence of branching networks of elastic fibers in the main substance (Fig. 4). The cartilage of the auricle, epiglottis, Vrisberg and Santorini cartilages of the larynx are built from it.

Fibrous cartilage (synonym for connective tissue) is located in the places of transition of dense fibrous connective tissue into hyaline cartilage and differs from the latter by the presence of real collagen fibers in the main substance (Fig. 5).

Cartilage pathology - see Chondritis, Chondrodystrophy, Chondroma.

Figure: 1-5. Cartilage structure.
Figure: 1. Cartilage histogenesis:
1 - mesenchymal syncytium;
2 - young cartilage cells;
3 - interlayers of the basic substance.
Figure: 2. Hyaline cartilage (low magnification):
1 - perichondrium;
2 - cartilage cells;
3 - basic substance.
Figure: 3. Hyaline cartilage (high magnification):
1 - isogenic group of cells;
2 - cartilaginous capsule;
3 - basophilic zone of the chondrin ball;
4 - oxyphilic zone of the chondrin ball;
5 - inter-territorial space.
Figure: 4. Elastic cartilage:
1 - elastic fibers.
Figure: 5. Fibrous cartilage.

The bone marrow, which fills the bone marrow cavities, contains mainly fats (up to 98% in the dry residue of the yellow marrow) and in smaller amounts choline phosphatides, cholesterol, proteins and minerals. The composition of fats is dominated by palmitic, oleic, stearic acids.
In accordance with the characteristics of the chemical composition, the bone is used for the production of semi-finished products, jellies, brawn, bone fat, gelatin, glue, bone meal.
Cartilage tissue. Cartilage tissue performs supporting and mechanical functions. It consists of a dense base substance, in which round-shaped cells, collagen and elastin fibers are located (Figure 5.14). Depending on the composition of the intercellular substance, hyaline, fibrous and elastic cartilages are distinguished. Hyaline cartilage covers the articular surfaces of the bones; costal cartilage and trachea are built from it. With age, calcium salts are deposited in the intercellular substance of such cartilage. The hyaline cartilage is translucent and has a bluish tint.

Ligaments between the vertebrae are made of fibrous cartilage, as well as tendons and ligaments where they attach to the bones. Fibrous cartilage contains many collagen fibers and a small amount of amorphous matter. It looks like a translucent mass.
Cream-colored elastic cartilage, in the intercellular substance of which elastin fibers predominate. Lime is never deposited in the elastic cartilage.

Cartilage tissue

It is part of the auricle, larynx.
The average chemical composition of cartilage tissue includes: 40-70% water, 19-20% proteins, 3.5% fats, 2-10% minerals, about 1% glycogen.
Cartilage is characterized by a high content of mucoprotein - chondromucoid and mucogulisaccharide - chondroitinsulfuric acid in the main intercellular substance. An important property of this acid is its ability to form salt-like compounds with various proteins: collagen, albumin, etc. This, apparently, explains the "cementing" role of mucopolysaccharides in cartilage tissue.
Cartilage tissue is used for food purposes, and gelatin and glue are produced from it. However, the quality of gelatin and glue is often not high enough, since mucopolysaccharides and glucoproteins pass into solution from the tissue along with gelatin, reducing the viscosity and strength of the jelly.

Cartilage tissue is a type of supporting tissue characterized by the strength and elasticity of the matrix. This is due to their position in the body: in the area of \u200b\u200bthe joints, in the intervertebral discs, in the wall of the respiratory tract (larynx, trachea, bronchi).

Cartilaginous

○ Hyaline

○ Elastic

○ Fibrous

However, the general plan of their structure is similar.

1. The presence of cells (chondrocytes and chondroblasts).

2. Formation of isogenic cell groups.

3. The presence of a large amount of intercellular substance (amorphous, fibers), which provides strength and elasticity - that is, the ability to reversible deformation.

4. Absence of blood vessels - nutrients diffuse from the perichondrium due to the high water content (up to 70–80%) in the matrix.

5. They are characterized by a relatively low metabolic rate.

Cartilage tissue

They have the ability to grow continuously.

In the process of development of cartilaginous tissue from the mesenchyme, a differention of cartilaginous cells is formed. It includes:

1. Stem cells are characterized by a rounded shape, a high value of nuclear-cytoplasmic ratios, a diffuse location of chromatin and a small nucleolus. Organelles of the cytoplasm are poorly developed.

2. Semi-stem cells (prechondroblasts) - the number of free ribs increases in them, gREPS appears, cells become elongated, the nuclear cytoplasmic ratio decreases. Like stem clumps, they exhibit low

proliferative activity.

3. Chondroblasts - young cells located on the periphery of the cartilage. They are small flattened cells capable of proliferation and synthesis of components of the intercellular substance. The basophilic cytoplasm has well-developed gREPS and

agrEPS, Golgi apparatus. In the process of development, they turn into chondrocytes.

4. Chondrocytes are the main (definitive) type of cartilage tissue cells. They can be oval, round or polygonal. Located in special cavities

- lacunae - intercellular substance, singly or in groups. These groups are called isogenic cell groups.

Isogenic cell groups - (from the Greek isos - equal, genesis - development) - groups of cells (chondrocytes) formed by division of one cell. They lie in a common cavity (lacuna) and are surrounded by a capsule formed by the intercellular substance of cartilage tissue.

The main amorphous substance (cartilage matrix) contains:

1. Water - 70-80%

2. Inorganic compounds - 4–7%.

3. Organic matter - 10-15%

- Glycosaminoglycans:

Ø chondroitin sulfates (chondroitin-6-sulfate, chondroitin-4-sulfate,

Ø hyaluronic acid;

- Proteoglycans.

- Chondronectin - this glycoprotein connects cells with each other and with various substrates (cell connection with type I collagen).

There are many fibers in the intercellular substance:

1. Collagen (I, II, VI types)

2. And in elastic cartilage - elastic.

Cartilage growth methods.

Interstitial cartilage growth is an increase in the volume of cartilage tissue (cartilage) due to an increase in the number of dividing chondrocytes and the accumulation of components of the intercellular substance secreted by these cells.

Appositional growth of cartilage is an increase in the volume of cartilage tissue (cartilage) due to the replenishment of cells located on the periphery (mesenchymal cells - during embryonic chondrogenesis, perichondroblasts chondroblasts - during the postembryonic period of ontogenesis).

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The structure of individual human tissues, types of cartilage

Tendons and ligaments. Force (pulling of muscles or external forces) acts on the tendons and ligaments in one direction. Therefore, the fibrous plates of the tendons, consisting of fibroblasts (fibrocytes), the main substance and collagen fibers, are located parallel to each other. Bundles (from 10 to 1000) of fibrous plates are separated from each other by layers of unformed connective tissue. Small bundles are combined into larger ones, etc. The entire tendon is covered with a thicker layer of loose tissue called the supra tendon. It carries blood vessels and nerves to the tendon, ligament; there are also germ cells.

Fasciae, muscle aponeuroses, capsules of joints and organs, etc. The forces acting on them are directed in different directions. The bundles of fibrous plates are located at an angle to each other, so the fascia and capsules are difficult to stretch and separate into separate layers.

Cartilage tissue. It can be permanent (for example, the cartilage of the ribs, trachea, intervertebral discs, menisci, etc.) and temporary (for example, in the zones of bone growth - metaphyses). The temporary cartilage is subsequently replaced by bone tissue. Cartilaginous tissue does not have connective tissue layers, vessels and nerves. Its trophism is provided only from the side of the perichondrium (the layer of fibrous connective tissue that covers the cartilage) or from the side of the bone. The growth layer of cartilage is located in the lower layer of the perichondrium. When damaged, the cartilage is poorly restored.

There are three types of cartilage:

1. Hyaline cartilage. Covers the articular surfaces of the bones, forms the cartilaginous ends of the ribs, the rings of the trachea and bronchi. In the elastic base substance (chondromucoid) of the cartilaginous plates, there are separate collagen fibers.

2. Elastic cartilage.

The structure and function of human cartilage

Forms the auricle, the wings of the nose, the epiglottis, the cartilage of the larynx. In the main substance of the cartilaginous plates, there are mainly elastic fibers.

3. Fibrous cartilage. Forms intervertebral and articular discs, menisci, articular lips. The cartilage plates are penetrated with a large number of collagen fibers.

Bone forms separate bones - the skeleton. It makes up about 17% of the total weight of a person. Bones are strong and lightweight. The strength and hardness of the bone is provided by collagen fibers, a special basic substance (ossein), impregnated with minerals (mainly hydroxyapatite-phosphoric acid lime) and the ordered arrangement of bone plates. Bone plates form the outer layer of any bone and the inner layer of the bone marrow cavity; the middle layer of the tubular bone is made up of special, so-called osteonic systems - multi-row, concentrically arranged plates around the canal, which contains the vessels, nerves, and loose connective tissue. The spaces between the osteons (tubes) are filled with intercalated bone plates. Osteons are located along the length of the bone or in accordance with the load. Very thin tubules extend from the osteon canal to the sides, connecting the separated osteocytes.

There are two types of bone - cortical (compact or dense), up to 80% and trabecular (spongy or porous), accounting for up to 20% of the total bone mass. If the osteons and insertion plates lie tightly, then a compact substance is formed. It forms the diaphysis of tubular bones, the top layer of flat bones and covers the cancellous part of the bone. At the ends of the bones, where a large volume is required for articular articulation while maintaining lightness and strength, a cancellous substance is formed. It consists of beams, beams (trabeculae) that form bone cells (like a sponge). The trabeculae are composed of osteons and intercalated bone plates, which are positioned in accordance with the pressure on the bone and with the muscle pull.

Outside, the bone, with the exception of the articular surfaces, is covered by the periosteum (a layer of connective tissue, from above - dense, and closer to the bone - loose). In the latter, there are many vessels, nerves, contains bone-like cells - osteoblasts, which contribute to the growth of bone in width and the healing of fractures.

The rate of renewal of cortical and trabecular bones in an adult is from 2.5 to 16% per year.

Cartilaginous and bone tissue develop from the sclerotome mesenchyme, belong to the tissues of the internal environment and, like all other tissues of the internal environment, consist of cells and intercellular substance. The intercellular substance is dense here, therefore these tissues perform a musculoskeletal function.

Cartilage tissue (textus cartilagineus). They are classified into hyaline, elastic and fibrous. The classification is based on the features of the organization of the intercellular substance. The cartilaginous tissue contains 80% water, 10-15% organic substances and 5-7% inorganic substances.

The development of cartilage tissue, or chondrogenesis, consists of 3 stages: 1) the formation of chondrogenic islets; 2) formation of primary cartilage tissue; 3) differentiation of cartilage tissue.

During 1st stage mesenchymal cells combine into chondrogenic islets, the cells of which multiply and differentiate into chondroblasts. The formed chondroblasts contain granular EPS, the Golgi complex, and mitochondria. Chondroblasts then differentiate into chondrocytes.

During 2nd stage in chondrocytes, granular EPS, Golgi complex, mitochondria are well developed. Chondrocytes actively synthesize fibrillar protein (type II collagen), from which the intercellular substance is formed, which is stained oxyphilically.

On the offensive 3rd stage in chondrocytes, granular EPS develops more intensively, on which fibrillar proteins and chondroitin sulfates (chondroitinsulfuric acid) are produced, which are stained with basic dyes. Therefore, the main intercellular substance of the cartilage tissue around these chondrocytes is basophilic.

Around the cartilaginous anlage of mesenchymal cells, the perichondrium is formed, consisting of 2 layers: 1) the outer, more dense, or fibrous, and 2) the inner, looser, or chondrogenic, which contains prehondroblasts and chondroblasts.

Appositional growth of cartilage, or growth by superimposition, characterized by the fact that chondroblasts are released from the perichondrium, which are superimposed on the main substance of the cartilage, differentiate into chondrocytes and begin to produce intercellular substance of the cartilage tissue.

Interstitial growth cartilage tissue is carried out by chondrocytes located inside the cartilage, which, firstly, divide by mitosis and, secondly, produce intercellular substance, thereby increasing the volume of cartilage tissue.

Cartilage cells (chondrocytus). Differon of chondrocytes make up: stem cell, half-stem cell (prechondroblast), chondroblast, chondrocyte.

Chondroblasts (chondroblastus) are located in the inner layer of the perichondrium, have organelles of general importance: granular EPS, Golgi complex, mitochondria. Functions of chondroblasts:

1) secrete intercellular substance (fibrillar proteins);

2) in the process of differentiation they turn into chondrocytes;

3) have the ability to mitotic division.

Chondrocytes located in cartilaginous lacunae. At first, there is 1 chondrocyte in the lacuna, then, in the process of its mitotic division, 2, 4, 6, etc. cells are formed. All of them are in one lacuna and form an isogenic group of chondrocytes.

Chondrocytes of the isogenic group are divided into 3 types: I, II, III.

Chondrocytes type I have the ability to mitotic division, contain the Golgi complex, mitochondria, granular EPS and free ribosomes, have a large nucleus and a small amount of cytoplasm (large nuclear-cytoplasmic ratio). These chondrocytes are located in the young cartilage.

Chondrocytes type II are located in mature cartilage, their nuclear-cytoplasmic ratio decreases somewhat, as the volume of cytoplasm increases; they lose the ability to mitosis. In their cytoplasm, granular EPS is well developed; they secrete proteins and glycosaminoglycans (chondroitin sulfates), so the main intercellular substance around them is stained basophilically.

Chondrocytes type III are in old cartilage, lose the ability to synthesize glycosaminoglycans and produce only proteins, therefore the intercellular substance around them is stained oxyphilically. Consequently, a ring is visible around such an isogenic group, which is stained oxyphilically (proteins are isolated by type III chondrocytes), outside of this ring, a basophilically stained ring is visible (glycosaminoglycans are secreted by type II chondrocytes), and the outer ring itself is again oxyphilic stained (proteins are isolated at a time when in cartilage were only young type I chondrocytes). Thus, these 3 differently colored rings around isogenic groups characterize the process of formation and function of chondrocytes of 3 types.

Intercellular substance of cartilage tissue. Contains organic matter (mainly type II collagen), glycosaminoglycans, proteoglycans and non-collagen type proteins. The more proteoglycans, the more hydrophilic the intercellular substance, the more elastic and more permeable it is. Gases, water molecules, salt ions and micromolecules diffusely penetrate through the main substance from the side of the perichondrium. However, macromolecules do not penetrate. Macromolecules have antigenic properties, but since they do not penetrate into the cartilage, the cartilage transplanted from one person to another takes root well (there is no immune rejection reaction).

In the main substance of the cartilage there are collagen fibers, consisting of type II collagen. The orientation of these fibers depends on the lines of force, and the direction of the latter depends on the mechanical effect on the cartilage. There are no blood and lymphatic vessels in the intercellular substance of the cartilage tissue, therefore, the nutrition of the cartilage tissue is carried out by diffuse influx of substances from the vessels of the perichondrium.

Hyaline cartilage tissue. It has a bluish-whitish color, translucent, fragile, in the body it is located at the junction of the ribs with the sternum, in the walls of the trachea and bronchi, larynx, on the articular surfaces. Depending on where the hyaline cartilage is located, it has a different structure. In case of malnutrition, hyaline cartilage undergoes calcification.

Shawl cartilage at the ends of the ribs covered with perichondrium, under which the zone of young cartilage is located. Here are young fusiform chondrocytes located in cartilaginous lacunae and capable of producing only fibrillar proteins. Therefore, the intercellular substance around them is colored oxyphilically. Ptubzhe chondrocytes are rounded. Isogenic groups of chondrocytes are formed even deeper, capable of producing proteins and chondroitinsulfuric acid, which is basophilic stained. Therefore, the intercellular substance around them is stained with basic dyes. Even deeper are isogenic groups containing even more mature chondrocytes, secreting only proteins. Therefore, the main substance around them is colored oxyphilically.

Hyaline cartilage of articular surfaces does not have perichondrium and consists of 3 indistinctly delimited zones from each other. The outer zone includes fusiform chondrocytes located in the lacunae parallel to the cartilage surface. Ptubrze is a columnar zone, the cells of which are continuously dividing and forming columns; the inner zone is divided by the basophilic line into uncharged and calcified parts. The calcified part adjacent to the bone tissue contains matrix vesicles and blood vessels.

Food this cartilage is carried out from 2 sources: 1) due to the nutrients found in the synevial \u200b\u200bfluid of the joint, and 2) due to the blood vessels passing through the calcified cartilage.

Elastic cartilage tissue. It has a whitish-yellowish color, is located in the auricle, the wall of the external auditory canal, arytenoid and horn-shaped cartilages of the larynx, epiglottis, in the bronchi of medium caliber. It differs from hyaline cartilage in that elastic cartilage is, first of all, elastic, since, in addition to collagen, it contains elastic fibers that go in different directions and are woven into the perichondrium and are stained with orsein in brown; secondly, it contains less chondroitinsulfuric acid, lipids and glycogen; thirdly, it never undergoes calcification. At the same time, the general plan of the structure of elastic cartilage tissue is similar to that of hyaline cartilage.

Fibrous cartilage (cartilago fibrosa). It is located in the intervertebral discs, pubic fusion, the places of attachment of tendons to the hyaline cartilage and in the maxillary joints. This cartilage is characterized by the presence of 3 sections: 1) the tendon part; 2) actually fibrous cartilage; 3) hyaline cartilage. Where there is a tendon, bundles of collagen fibers run parallel to each other, fibrocytes are located between them; in the fibrous cartilaginous tissue, the parallel arrangement of the fibers is preserved, chondrocytes are located in the lacunae of the cartilaginous substance; hyaline cartilage has a normal structure.

Age-related changes in cartilage tissue. The greatest changes are observed in old age, when the number of chondroblasts in the perichondrium and the number of dividing cartilage cells decrease. In chondrocytes, the amount of granular EPS, the Golgi complex and mitochondria decreases, the ability of chondrocytes to synthesize glycosaminoglycans and proteoglycans is lost. A decrease in the amount of proteoglycans leads to a decrease in the hydrophilicity of the cartilage tissue, a weakening of the permeability of the cartilage and the supply of nutrients. This leads to calcification of the cartilage, the penetration of blood vessels into it and the formation of bone matter inside the cartilage.

Bone tissue. Bone tissues are characterized by the presence of dense intercellular substance in them. Bone tissue functions: 1) support-mechanical and 2) deposit of salts. Bone tissue contains 70% mineral salts, the rest is water and organic matter. Among organic substances, type I collagen prevails, there are non-collagen proteins, citric and chondroitin sulfuric acids, osteonectin (an adhesive).

Bone classification based on the location (orientation) of collagen fibers. On this basis, bone tissue is divided into: 1) reticulofibrous and 2) lamellar.

Reticulofibrous bone tissue characterized by coarse bundles of collagen fibers oriented in different directions. In the intercellular substance there are process-shaped osteocytes located in the bone lacunae. After birth, this tissue is present in the fusion of the bones of the skull and in the places of attachment of the tendons to the bone tissue.

Lamellar bone tissue characterized by the fact that collagen fibers are parallel to each other and form plates.

Bone cells include 2 diferons: 1) the diferon of osteocytes (mechanocytes), includes osteogenic stem cells, semi-stem stromal cells, osteoblasts, osteocytes; 2) the diferon of osteoclasts. Skeletal stem (osteogenic) cells can differentiate in different directions (into osteoblasts, cells of the stroma of the red bone marrow).

Differon osteocytes (mechanocytes). Osteoblastsare located in the periosteum, endosteum, in the canals of osteons and in places of bone tissue regeneration; have an elongated shape, length 15-20 μm, oval nucleus, oxyphilic or basophilic cytoplasm, contain well-developed granular EPS, Golgi complex and mitochondria, high alkaline phosphatase activity, do not have the ability to mitotic division.

Osteoblast functions:

1) secretory (produce an adhesive substance osteonectin, type I collagen, from which collagen fibers, chondroitin sulfates, citric acid polymerize);

2) participate in the mineralization of bone tissue due to the release of alkaline phosphatase.

Osteocytes located in bone lacunae, repeating the shape of these cells. The processes of osteocytes penetrate into the bone tubules extending from the lacunae. In osteocytes, organelles of general importance are poorly developed, nuclei with coarse lumps of chromatin, do not contain nucleoli (inactive), and their functional activity is reduced in comparison with osteoblasts.

The functional significance of osteocytes is to maintain bone homeostasis.

Differon of osteoclasts. The first cell is HSC, then a number of developing hematopoietic cells, then a monocyte, which migrates through the capillary wall into bone tissue and turns into an osteoclast (macrophage).

The size of osteoclasts reaches 90 microns, their shape is round, oval, elongated, irregular. From the surface adjacent to the bone tissue, the osteoclast has 2 zones: 1) central, or corrugated; 2) peripheral (tight fitting zone). There are few organelles in the tight fitting zone, it is dense. The significance of this zone lies in the fact that the osteoclast adheres tightly to the bone substance and creates an airtight space in the area of \u200b\u200bthe corrugated zone.

The corrugated zone is represented by outgrowths on the surface of which enzymes are adsorbed. Above the corrugated zone, there are various vacuoles, well-developed lysosomes containing proteolytic enzymes, and mitochondria. In the cytoplasm of osteoclasts, there are from 3 to several tens of nuclei. Osteoclasts are localized in the perivascular spaces of osteons and in places of bone tissue regeneration.

Osteoclast function - destruction of the intercellular substance of bone tissue using proteolytic enzymes of lysosomes. To activate enzymes, osteoclasts produce carbon dioxide, which, when interacting with water, turns into carbonic acid, and an acidic environment is created in which the components of bone tissue dissolve well.

Bone development (osteogenesis). Bone tissue develops in 2 ways: 1) direct osteogenesis and 2) indirect osteogenesis. Direct osteogenesis characterized by the fact that the bone substance develops directly from the mesenchyme. This is the way flat bones develop. Indirect osteogenesis characterized by the fact that at first a cartilaginous model of the future bone is formed, consisting of hyaline cartilage, then a tubular bone is formed in place of this model.

Direct osteogenesis includes 4 stages of development:

1) the formation of osteogenic islets;

2) the formation of osteoid tissue;

3) mineralization;

4) the development of lamellar bone tissue in place of reticulofibrous bone tissue.

1st stage characterized by the fact that mesenchymal cells form osteogenic islets. Islet cells differentiate into osteoblasts, in the cytoplasm of which granular EPS, Golgi complex, mitochondria, and ALP are well developed.

During 2nd stage osteoblasts secrete type I collagen, osteonectin, i.e. intercellular substance. As a result, osteoid (non-mineralized) beams are formed, which have an elongated shape. On the surface of these beams, osteoblasts continue to deposit intercellular substance, while the beams are lengthened and thickened. In the process of secretory activity, some of the osteoblasts walled themselves up in the intercellular substance and turns into osteocytes located in the lacunae. Instead, new osteoblasts differentiate from the mesenchyme, which continue to deposit extracellular substance. The resulting beams are connected at their ends, intertwined, and an osteoid substance is formed.

On the offensive 3rd stage ALP is released from osteoblasts, which decomposes glycerophosphates into phosphoric acid and carbohydrates. Phosphoric acid combines with calcium, resulting in the formation of calcium phosphate, which is deposited as an amorphous substance in the osteoid tissue. As a result of further transformations, calcium phosphate is converted into hydroxyapatite crystals, which adhere to each other and to collagen fibers with the help of osteonectin.

Matrix bodies with a diameter of 1 μm, containing glycogen and alkaline phosphatase, take part in the mineralization of bone tissue. Calcium is deposited in these little bodies. Matrix bodies are formed as a result of protrusion of the cytolemma of osteoblasts and are separated from these cells. Their participation in mineralization consists of 2 periods: 1) the formation of crystals inside the vesicles and 2) rupture of the vesicle membrane, the release of the crystal into the intercellular space and sticking it to the collagen fiber using osteonectin (an adhesive produced by osteoblasts).

As a result of mineralization, reticulofibrous tissue is formed, which is also called primary cancellous bone tissue. Around this tissue, the periosteum is formed from mesenchymal cells, which consists of 2 layers: 1) an internal loose osteogenic, in which osteoblasts are located, and 2) an external fibrous, more dense one.

When 4th stage blood vessels, osteoblasts and mesenchymocytes penetrate from the periosteum into the formed bone tissue. Monocytes migrate through the capillary wall into the bone substance, which differentiate into osteoclasts. Osteoclasts begin to destroy the reticulofibrous bone tissue, making cavities of various shapes in it. Around the blood vessels located in these cavities (lacunae), osteoblasts begin to form bone plates, superimposing them one on top of the other and walled themselves in the bone substance, turning into osteocytes. Bone plates layered on top of each other are called osteons. Osteons, intertwining, form a cancellous bone tissue. Between the intertwining osteons, there are mesenchymal and osteogenic cells, layers of connective tissue in which blood vessels pass. So reticulofibrous bone tissue turns into lamellar.

Due to the osteoblasts of the inner layer of the periosteum, common external bone plates begin to form around the bone rudiment, layering one on top of the other, as a result of which the entire forming bone is surrounded by several common bone plates.

Subsequently, the formed lamellar bone tissue is destroyed by osteoclasts, in the formed lacunae around the vessels, osteoblasts form new osteons. This remodeling of bone tissue continues throughout life.

Indirect osteogenesis characterized by the fact that at first a cartilaginous model of the future bone is formed, consisting of hyaline cartilage. This model has 1 diaphysis and 2 pineal glands. The ossification process begins first in the area of \u200b\u200bthe diaphysis. In this case, osteoblasts are evicted from the perichondrium, which form a perichondral cuff around the cartilaginous diaphysis, consisting of reticulofibrous (coarse-fibrous) bone tissue. The diaphysis cartilage inside this cuff undergoes degenerative changes and mineralization. Chondrocytes vacuolize, their nuclei are pyknotized, and as a result they turn into vesicular chondrocytes.

At this point, the perichondrium is transformed into the periosteum. From the side of the latter, blood vessels grow in through the perichondral bone cuff to the calcified hyaline cartilage, along with which mesenchymocytes, osteoblasts and osteoclasts enter. Osteoclasts or chondroclasts begin to destroy the calcified cartilage, forming lacunas of various shapes in it. On the walls of cavities (lacunae), osteoblasts deposit a bone substance called endochondral bone. The peculiarity of the endochondral bone is that its bone substance contains areas of mistletoe (calcified) cartilage.

The process of enchondral bone formation is called enchondral ossification. The enchondral bone is again destroyed by osteoclasts, resulting in the formation of a medullary cavity. The mesenchymocytes that have penetrated this cavity form an endosteum, which corresponds to the periosteum (periosteum) and lines the medullary cavity from the inside.

The reticular stroma of the red bone marrow is formed from the mesenchyme of the bone marrow cavity. Stem cells enter this stroma, and the process of hematopoiesis begins.

The reticulofibrous tissue of the perichondral bone cuff is also destroyed by osteoclasts, which make elongated cavities in it. Around the blood vessels of these cavities, osteoblasts develop cylindrical bone plates, layering them on top of each other, resulting in the formation of osteons oriented along the longitudinal axis of the tubular bone. At the same time, osteoblasts stand out from the side of the periosteum, which form common external bone plates around the diaphysis, also layering them on top of each other. At the same time, from the side of the endosteum, osteoblasts form internal common bone plates. As a result, 3 layers of the diaphysis are formed: 1) external common bone plates; 2) a layer of osteons; 3) internal common bone plates and inside - the bone marrow cavity.

Pineal gland development: at the moment when the perichondral bone cuff has formed around the diaphysis, the cartilaginous pineal gland continues to grow. There are 3 zones in the pineal gland:

1) the outer, or distal, part, which is called the zone of free chondrocytes (zona reservata);

2) the columnar zone of chondrocytes (zona collumnare), in which chondrocytes divide by mitosis and are superimposed on each other in the form of columns;

3) a zone of vesicular chondrocytes, characterized by the fact that chondrocytes hypertrophy, vacuolize and turn into vesicular, and the intercellular substance around them is mineralized.

From the side of the diaphysis, the calcified cartilaginous pineal gland is subjected to destruction by osteoclasts, on the walls of the formed cavities, osteoblasts deposit bone substance. This is how the bony diaphysis grows due to the calcified vesicular zone of the cartilaginous pineal gland.

The cartilaginous pineal gland increases in size, therefore it is difficult for nutrients to penetrate into the center of the pineal gland, as a result of which it undergoes mineralization. Blood vessels grow to the mineralized center of the cartilaginous pineal gland, along with which osteoclasts and osteoblasts enter this place, due to which the bone substance of the pineal gland is formed. However, between the bony epiphysis and the diaphysis, cartilage remains, called the metaepiphyseal growth plate. Due to this plate, the growth of the tubular bone continues in length - in boys up to 25 years of age, in girls up to 18 years old.

In the metaepiphyseal growth plate, 3 zones are distinguished:

1) the border zone, located on the border with the bony pineal gland, where the cells are arranged irregularly;

2) a columnar zone, where proliferating chondrocytes overlap and are arranged in columns;

3) a zone of vesicular chondrocytes, around which there is a calcified intercellular substance. This zone is constantly destroyed by osteoclasts and, with the help of osteoblasts, is converted into bone tissue of the diaphysis.

Thus, in the metaepiphyseal growth plate, 2 processes occur simultaneously: 1) proliferation, i.e., multiplication of chondrocytes, due to which this plate should have thickened, and 2) resorption of the calcified part of this plate and its replacement with bone tissue. Therefore, this plate does not thicken and does not become thinner until the moment the bone growth stops in length. Bone growth stops with the disappearance of the metaepiphyseal plate.

The growth of the bone in thickness is carried out due to the osteoblasts of the periosteum, due to which common bone plates are formed, which are superimposed on each other.

Lamellar bone tissue is subdivided into: 1) compact bone substance (diaphysis of tubular bones) and 2) cancellous bone substance (epiphysis of tubular bones and flat bones). The structural and functional unit of fine-fibrous (lamellar) bone tissue (cancellous or compact) is bone plate ... The structural and functional unit of the compact bone substance is osteon .

The structure of the diaphysis of the tubular bone (compact substance of bone tissue). The diaphysis of the tubular bone is covered from the outside by the periosteum, and from the side of the medullary cavity by the endostome. Between the periosteum and the endosteum, there is a compact bone substance of the diaphysis, consisting of 3 layers:

1) a layer of external common bone plates;

2) a layer of osteons and insertion plates;

3) a layer of internal common bone plates.

Layer external bone plates represented by 8-10 bone plates, 4-15 microns thick. In each bone lamina, collagen fibers are parallel, and the fibers of one lamina are located at an angle with respect to the fibers of the adjacent lamina. From the side of the periosteum, collagen (Sharpey) fibers and perforating canals penetrate into the layer of the outer bone plates and the perforating channels in which the arteries (supplying vessels) pass. In each bone plate there are process-shaped osteocytes located in the bone lacunae.

External common bone plates are in the form of open cylinders. They overlap each other, surrounding the diaphysis on all sides.

Osteon layer consists of osteons and insertion plates. Osteon is a structural unit of bone tissue, consisting of cylindrical bone plates, as if inserted into one another. In the center of the osteon there is a channel through which blood vessels pass. The canals of osteons are connected to each other by perforating canals. Through these channels, the blood vessels of the osteons anastomose with each other. Through the system of blood vessels passing in the canals of osteons and perforating canals, blood enters the marrow cavity. Osteons are connected to each other using cleavage lines.

Insert plates, located between the osteons, are the remains of the destroyed primary generation osteons. In the insertion plates and the plates of osteons, there are osteocytes in the bone lacunae. The lacunae are connected to each other using bone tubules. These tubules circulate fluid that feeds the bone tissue, so these tubules are called bone nutrient tubules.

Internal common bone plates have the same structure as the outer bone plates, and separate the layer of osteons from the medullary cavity.

Cancellous bone tissue also represents a lamellar (fine-fibrous) bone tissue and also consists of osteons formed by bone plates. These osteons are intertwined with each other and have a slightly modified shape. The structural unit of the spongy substance is bone plate ... Fine-fibrous bone tissue is formed by collagen fibers formed into plates. Red bone marrow is located between the beams of the cancellous bone tissue.

In the trophism of bone tissue vessels of the periosteum, vessels of osteon canals, vessels of perforating canals and vessels of the endosteum take part. Nutrients from the perivascular spaces enter the bone nutrient tubules and are distributed through these tubules throughout the bone tissue. Nutrients cannot diffusely penetrate into the intercellular substance of bone tissue, since this is prevented by its mineralization.

Rebuilding of bone tissue and the influence of internal and external factors on the restructuring process. Bone tissue undergoes reconstruction throughout life with the participation of osteoclasts and osteoblasts. Osteoclasts destroy bone substance by making cavities in it. Around the blood vessels of these cavities, osteoblasts produce bone substance in the form of cylindrical bone plates that overlap each other. Thus, in place of the old destroyed osteons, new ones appear.

The restructuring process is influenced by external and internal factors. External factors primarily include mechanical stress. With its increase, the activity of osteoblasts increases, as a result of the functional activity of which the number of osteons increases, which contributes to the compaction and increase in the strength of the bone tissue.

With a reduced mechanical load, the activity of osteoclasts increases, which destroy the intercellular substance of bone tissue, weakening its density and strength. The activity of osteoclasts is especially increased in a state of weightlessness. Therefore, astronauts are forced to perform special exercises with a load on the skeletal system, otherwise their bone skeleton would change so much that it would not be able to perform the musculoskeletal function.

Piezoelectric effect characterized by the fact that an electric potential is formed on the concave and convex surfaces of the bone plates of the bone tissue. On the surface of the bone plate, where there is a positive potential, osteoclasts are activated, destroying the bone substance; where negative potential - osteoblasts that produce bone substance are activated. The piezoelectric effect is used by surgeons. In the place where the bone needs to be grown, they artificially create a negative potential.

Especially strong influence on the reconstruction of bone tissue is exerted by vitamins C, D, A. Under the influence of vitamin C, osteoblasts are activated, the release of collagen molecules increases, from which collagen fibers polymerize; the alkaline phosphatase activity of osteoblasts increases, as a result of which the mineralization of bone substance increases. With a lack of vitamin C, these processes are weakened, bone tissue softens, and its density decreases.

With a lack of vitamin D, bone mineralization is impaired, which softens at the same time; deformation of bones is noted, which is observed in childhood. This disease is called rickets.

With an excess of vitamin A, osteoclasts are activated, destroying bone substance.

The influence of internal factors. Influence of hormones.With a lack thyroxine the activity of osteoblasts decreases, as a result of which a picture is observed that resembles that with a lack of vitamin C, i.e., the formation of collagen fibers and bone mineralization are disrupted.

Effect of excess calcitonin consists in increasing the mineralization of bone tissue, since blood calcium is deposited in the bones.

Effect of excess parathyrin lies in the fact that the function of osteoclasts is activated, since there are receptors for parathyrin on their cytolemma. The calcium released after the destruction of the bone substance enters the blood, i.e., the bone tissue is demineralized.

The effect of a lack of growth hormone the pituitary gland is manifested in impaired bone growth.

Impact of a lack of sex hormones in adolescence, it is characterized by the fact that the reverse development of the metaepiphyseal growth plate slows down, so the tubular bones become prohibitively long. With an excess of sex hormones in adolescence, the metaepiphyseal growth plate prematurely disappears and the length of the tubular bones of the extremities stops.

With a lack of sex hormones in women after the onset of menopause, a violation of the structure of bone tissue is observed. However, this is easily corrected by the appointment of the appropriate sex hormones.

Bone regeneration in case of damage. As a result of injuries, bone fractures of the limbs are usually observed. As a result of the fracture, 2, and sometimes more, of its fragments are formed. After a bone fracture, osteoclasts migrate to the ends of the fragments, destroying the necrotic areas of the bone tissue, that is, they clean up the ends of the fragments. Then, with the participation of osteoblasts, bone substance is produced that connects the ends of the fragments. First

an osteoid substance (soft callus) is formed, which then undergoes mineralization (hard callus). The process of fusion of bone fragments can be accelerated if, on the first day after the fracture, the patient is prescribed vitamin A, which increases the activity of osteoclasts, i.e. cleaning the ends of the fragments, and then prescribes vitamin C, which activates the function of osteoblasts, which produce type I collagen, glycosaminoglycans and ostenectin and in the mineralization of soft corn. With a lack of vitamin C, the fusion of bone fragments will be slowed down, and a false joint may form.

Connections of bones. Bone joints are subdivided into: 1) continuous (syndesmosis, synchondrosis and synostosis) and 2) intermittent (joints).

Syndesmoses characterized by the connection of bones using dense connective tissue (parietal sutures of the skull, connective tissue membrane between the ulna and radius of the forearm).

Synchondrosis - connection with cartilage (intervertebral discs).

Synostosis - dense bone joints without fibrous connective tissue (joints of the pelvic bones).

Joints they consist of articulated surfaces covered with cartilage and an articular bag (capsule). The articular capsule consists of 2 layers: 1) external and 2) internal (synevial).

Outer layer represented by densely formed connective tissue.

Interior (synovial) layer consists of:

1) deep fibrous collagen-elastic layer;

2) superficial fibrous collagen-elastic layer;

3) the integumentary layer adjacent to the superficial fibrous collagen.

Covering the layer consists of cells - 3 types of syneviacytes: a) macrophage; b) synovial fibroblasts and c) intermediate.

Bone and cartilage tissue make up the human skeleton. These tissues are entrusted with a supporting function, along with this they protect the internal organs, organ systems from adverse factors. For the normal functioning of the human body, it is necessary that all naturally occurring cartilages are in anatomically correct places, so that the tissues are strong and regenerate as needed. Otherwise, a person is faced with many unpleasant diseases that lower the standard of living, or even make it impossible to move independently.

Features of the fabric

Tissue, like any other structural elements of the body, is formed from special cells. Cartilage cells in science are called diferons. This concept is complex, it includes several types of cells: stem, semi-stem, united within the framework of anatomy in a group of little specialized ones - this category is inherent in the ability to actively divide. Chondroblasts are also isolated, that is, those cells that can divide, but at the same time are able to produce intercellular connections. Finally, there are cells whose main task is to create an intermediate substance. Their specialized name is chondrocytes. In the composition of these cells there are not only fibers of cartilage tissue, the function of which is to ensure stability, but also the main substance, which scientists call amorphous. This compound is able to bind water, so that the cartilage tissue resists compression stresses. If all the cells of the joint are healthy, it will be elastic and strong.

In science, there are three types of cartilage tissue. For division into groups, the features of the intercellular connecting component are analyzed. It is customary to talk about the following categories:

• elastic;
• hyaline;
• fibrous.

And if in more detail?

As is known from anatomy, all types of cartilage have their own characteristic features. So, elastic tissue is distinguished by the specifics of the structure of the intercellular substance - it is characterized by a rather high concentration of collagen fibers. At the same time, such fabric is rich in amorphous substance. At the same time, this fabric has a high percentage of elastic fibers, which gave it its name. The functions of the elastic-type cartilage tissue are associated with this feature: providing elasticity, flexibility, persistent resistance to external influences. What more interesting anatomy can tell? Where is this type of cartilage located? Usually - in those organs that are naturally provided for bending. For example, the laryngeal cartilage, nose and ear shells, and the center of the bronchi are composed of elastic cartilage tissue.

Fibrous fabric: some features

At the point from which the hyaline cartilage begins, the fibrous connective tissue ends. Usually, this tissue is found in the discs between the vertebrae, as well as at the junction of bones, where mobility is not important. The structural features of this type of cartilage tissue are directly related to the specifics of its location. Tendons, ligaments at the point of contact with the cartilage tissue provoke an actively developed system of collagen fibers. The peculiarity of such tissue is the presence of cartilage cells (instead of fibroblasts). These cells form isogenic groups.

What else do you need to know

The course of human anatomy allows you to clearly understand what cartilage tissue is needed for: to ensure mobility while maintaining elasticity, stability, security. These fabrics are dense and provide mechanical protection. Modern anatomy as a science is characterized by an abundance of terms, including those complementary and mutually replacing each other. So, if we are talking about the vitreous cartilage tissue of the spine, then it is assumed that they are talking about hyaline. It is this tissue that forms the ends of the bones that make up the rib cage. Some elements of the respiratory system are also created from it.

The function of cartilage tissue from the category of connective tissue is the connection of tissue and hyaline vitreous cartilage, which has a completely different structure. But the reticular cartilage tissue ensures the normal functioning of the epiglottis, the hearing system, and the larynx.

Why is cartilage tissue needed?

Nature does not create anything for nothing. All tissues, cells, organs have a fairly extensive functionality (and some tasks are still hidden from scientists). As is already known from anatomy today, the functions of cartilage tissue include a guarantee of the reliability of the connection of elements that provide a person with the ability to move. In particular, the bony elements of the spine are connected with each other by cartilage tissue.

As it was possible to establish in the course of studies on aspects of nutrition of cartilage tissue, it takes an active part in carbohydrate metabolism. This explains some of the features of regeneration. It is noted that in childhood, the restoration of cartilaginous tissue is possible by 100%, but after years this ability is lost. If an adult is faced with damage to the cartilage tissue, he can only rely on partial restoration of mobility. At the same time, the restoration of cartilage tissue is one of the tasks attracting the attention of the leading medical minds of our time, therefore it is assumed that it will be possible to find an effective pharmaceutical solution to this problem in the near future.

Joint problems: there are options

Currently, medicine can offer several methods for restoring organs and tissues damaged for various reasons. If the joint has received a mechanical injury or a certain disease has provoked the destruction of biological material, in most cases, prosthetics becomes the most effective solution to the problem. But injections for the cartilage tissue will help when the situation has not gone so far, degenerative processes have begun, but are reversible (at least partially). As a rule, they resort to means that contain glucosamine, sodium sulfate.

Understanding how to restore cartilage tissue at the initial stages of the disease, they usually resort to physical exercise, strictly monitoring the level of stress. A good effect is shown by therapy using inflammation-blocking drugs. As a rule, most patients are prescribed medications that are rich in calcium in a form that is easily absorbed by the body.

Cartilaginous connective tissue: where do the problems come from?

In most cases, the disease is provoked by previous injuries or infection of the joint. Sometimes the degeneration of cartilaginous connective tissue is provoked by increased loads falling on it for a long time period. In some cases, problems are associated with genetic backgrounds. Hypothermia of body tissues can play a role.

In case of inflammation, the use of drugs for external use and tablets can give a good result. Modern medicines are formed taking into account the hydrophilicity characteristic of the cartilaginous tissue of the spine and other organs. This means that topical agents can quickly "get" to the affected area and have a therapeutic effect.

Structural features

As can be seen from the anatomy, hyaline cartilage, other cartilage tissues, as well as bone are grouped into the skeletal category. In Latin, this group of tissues is called textus cartilaginus. Up to 80% of this tissue is water, from four to seven percent is salt, and the rest is organic components (up to 15%). The dry part of cartilage tissue is half or more (up to 70%) formed from collagen. The matrix produced by tissue cells is a complex substance that includes hyaluronic acid, glycosaminoglycans, proteoglycans.

Tissue cells: some features

As scientists have found out, chondroblasts are young cells that usually have an irregular elongated shape. In the process of vital activity, such a cell generates proteoglycans, elastin, and other components essential for the normal functioning of the joint. The cytolemma of such a cell is a large number of microvilli. The cytoplasm contains an abundance of RNA. Such a cell is characterized by an endoplasmic reticulum of a high level of development, presented both in a non-granular form and in a granular one. The cytoplasm of chondroblasts also contains glycogen granules, the Golgi complex, and lysosomes. Usually the nucleus of such a cell has one or two nuclei. The formation contains a large amount of chromatin.

A distinctive feature of chondrocytes is their large size, since these cells are already mature. They are characterized by a round, oval, polygonal shape. Most chondrocytes are equipped with processes, organelles. Typically, such cells occupy lacunae, and around them is an intercellular connective substance. When a lacuna contains one cell, it is classified as primary. Isogenic groups consisting of a pair or three of cells are predominantly observed. This allows us to speak of a secondary lacuna. The wall of this formation has two layers: on the outside it is made of collagen fibers, and on the inside it is lined with proteoglycan aggregates interacting with the cartilaginous glycocalyx.

Biological features of tissue

When the cartilaginous tissue of the joint is in the focus of attention of scientists, it is usually studied as an accumulation of chondrons - this is the name given to the functional, structural units of biological tissue. A chondron is formed from a cell or a combined group of cells, a matrix surrounding the cell, and capsule-shaped lacunae. Each of the three types of cartilage listed above has its own unique structural features. For example, hyaline cartilage, which got its name from the Greek word for "glass", has a bluish tint and is characterized by cells of the most varied shapes and structures. Much depends on what place the cell occupies inside the cartilage tissue. Usually, hyaline cartilage is formed by groups of chondrocytes. Such tissue creates joints, rib cartilage, larynx.

If we consider the process of bone formation in the human body, you can see that at the initial stage, most of them consist of hyaline cartilage. Over time, the transformation of articular tissue into bone occurs.

What else is special?

But fibrous cartilage is very strong, as it consists of thick fibers. Its cells are characterized by an elongated shape, a rod-shaped nucleus and cytoplasm, which forms a small rim. Such cartilage usually creates fibrous rings characteristic of the spine, menisci, discs inside the joints. Cartilage covers some of the joints.

If we consider the elastic cartilage tissue, you will notice that it is quite flexible, since the matrix is \u200b\u200brich not only in collagen, but also in elastic fibers. This tissue is characterized by rounded cells enclosed in lacunae.

Cartilage and cartilage tissue

These two terms, despite their similarities, should not be confused. Cartilage is a type of connective biological tissue, while cartilage is an anatomical organ. In its structure, there is not only cartilage tissue, but also the perichondrium, which covers the tissues of the organ from the outside. In this case, the perichondrium does not cover the articular surface. This element of cartilage is formed by a connective tissue made up of fibers.

The perichondrium consists of two layers: fibrous, covering it from the outside, and cambial, with which the organ is lined inside. The second is also known as sprout. The inner layer is an accumulation of poorly differentiated cells. These include chondroblasts in an inactive stage, prechondroblasts. From these cells, chondroblasts are first formed, then they progress to chondrocytes. But the fibrous layer is distinguished by a developed circulatory network, represented by an abundance of blood vessels. The perichondrium is both a protective layer and a storage of material for regenerative processes, and a tissue, thanks to which the trophism of cartilaginous tissue is realized, in the structure of which there are no vessels. But if we consider hyaline cartilage, then in it the main tasks for trophism fall on the synovial fluid, and not only on the vessels. The blood supply to the bone tissue plays a very important role.

How it works?

The basis for the formation of cartilage, cartilage tissue is the mesenchyme. The process of tissue growth in science is called chondrogistogenesis. Mesenchymal cells at points where nature provides for the presence of cartilaginous tissue multiply, divide, grow, and round up. This results in a cell clump called a focus. Science usually refers to such places as chondrogenic islets. As the process moves forward, differentiation into chondroblasts occurs, due to which the production of fibrillar proteins that enter the environment between living cells becomes real. This leads to the formation of the first type of chondrocytes, capable of not only producing specialized proteins, but also a number of other compounds that are indispensable for the normal activity of organs.

As the cartilage tissue develops, chondrocytes differentiate, which leads to the formation of the second and third types of cells in this tissue. At the same stage, gaps appear. The mesenchyme, located around the cartilaginous islet, becomes the source of cells for the creation of the perichondrium.

Features of tissue growth

The development of cartilage is usually divided into two stages. First, the tissues go through a period of interstitial growth, during which chondrocytes actively multiply and produce intercellular substance. Then comes the stage of oppositional growth. Here "the main characters" are the chondroblasts of the perichondrium. In addition, tissue overlays located at the periphery of the organ provide irreplaceable assistance for the formation and functioning of cartilage tissue.

With the aging of the body as a whole, cartilaginous tissue in particular, degenerative processes are outlined. The most prone to such are hyaline cartilage. Elderly people are often faced with pain provoked by salt deposits in the deep cartilage layers. Calcium compounds accumulate more often, which leads to tissue blurring. The vessels grow into the affected area, the cartilage tissue is gradually transformed into bone. In medicine, this process is called ossification. But elastic tissues are not damaged by such changes, they do not ossify, although they lose elasticity over the years.

Cartilage tissue: degeneration problems

It so happened that from the point of view of human health, cartilage tissue is one of the most vulnerable, and almost all elderly people, and often the younger generation, suffer from diseases associated with joints. There are many reasons for this: it is the ecology, and the wrong way of life, and the wrong diet. Of course, very often we get injured, we face infections or inflammations. A one-time problem - injury or illness - passes, but at an older age it returns with echoes - joint pain.

Cartilage is quite sensitive to many diseases. Problems with the musculoskeletal system arise if a person is faced with a hernia, dysplasia, arthrosis, arthritis. Some suffer from a lack of natural collagen synthesis. With age, chondrocytes degenerate, and cartilage tissue suffers greatly from this. In many cases, the best therapeutic effect is provided by surgery, when the affected joint is replaced with an implant, but this solution is not always applicable. If there is a chance of restoring natural cartilage tissue, this chance should not be neglected.

Joint diseases: how do they manifest?

The majority of those suffering from such pathologies can more accurately predict the change in weather than any forecast: the joints affected by the disease respond to the slightest changes in the surrounding space with excruciating, pulling pain. If the patient suffers from joint damage, he cannot move abruptly, since the tissues react to this with sharp, severe pain. As soon as similar symptoms begin to appear, you need to immediately make an appointment with a doctor. It is much easier to cure a disease or block its development if you start the fight at an early stage. Delay leads to the fact that regeneration becomes completely impossible.

To restore the normal functionality of cartilage tissue, quite a few drugs have been developed. Mostly they are classified as non-steroidal and are designed to block inflammation. Also produced are pain relievers - pills, injections. Finally, recently, special chondroprotectors have become widespread.

How to treat?

The most effective remedies against degenerative processes in cartilage tissue affect the cellular level. They block inflammatory processes, protect chondrocytes from the negative effects, and also stop the degenerative activity of various aggressive compounds that attack cartilage tissue. Once the inflammation has been effectively blocked, the next step in therapy is usually to restore the intercellular junction. For this, chondroprotectors are used.

Several agents of this group have been developed - they are built on different active components, which means that they differ in the mechanism of action on the human body. For all funds in this group, effectiveness is characteristic only when taken in a long course, which allows you to achieve really good results. Particularly widespread are preparations made on chondroitin sulfate. It is glucosamine, which is involved in the formation of cartilage proteins and helps restore tissue structure. Due to the supply of a substance from an external source to all types of cartilage tissue, the process of production of collagen, hyalic acid is activated, and the cartilage is independently restored. With the correct use of medicines, you can quickly restore joint mobility and get rid of pain.

Another good option is products containing other glucosamines. They restore tissue from all sorts of damage. Under the influence of the active component, the metabolism in the cartilaginous tissues of the joint is normalized. Also recently used drugs of animal origin, that is, made from biological material obtained from animals. Most often these are the tissues of calves, aquatic creatures. Good results are shown by therapy using mucopolysaccharides and medicines based on them.

Cartilage is a skeletal connective tissue that has a supporting, protective and mechanical function.

Cartilage structure

Cartilage tissue consists of cells - chondrocytes, chondroblasts and dense intercellular substance, consisting of amorphous and fibrous components.

Chondroblasts

Chondroblasts are located singly along the periphery of the cartilaginous tissue. They are elongated flattened cells with a basophilic cytoplasm containing a well-developed granular endoplasmic reticulum and the Golgi apparatus. These cells synthesize the components of the intercellular substance, release them into the intercellular environment and gradually differentiate into definitive cells of the cartilage tissue - chondrocytes.

Chondrocytes

Chondrocytes by degree of maturity, according to morphology and function, they are subdivided into type I, II and III cells. All types of chondrocytes are localized in the deeper layers of cartilage tissue in special cavities - lacunae.

Young chondrocytes (type I) divide mitotically, but daughter cells find themselves in one lacuna and form a group of cells - an isogenic group. The isogenic group is a common structural and functional unit of cartilage tissue. The location of chondrocytes in isogenic groups in different cartilage tissues is not the same.

Intercellular substance cartilage tissue consists of a fibrous component (collagen or elastic fibers) and an amorphous substance, which contains mainly sulfated glycosaminoglycans (primarily chondroitin sulfuric acids), as well as proteoglycans. Glycosaminoglycans bind large amounts of water and determine the density of the intercellular substance. In addition, the amorphous substance contains a significant amount of mineral substances that do not form crystals. Vessels in the cartilaginous tissue are normally absent.

Cartilage classification

Depending on the structure of the intercellular substance, cartilaginous tissues are divided into hyaline, elastic and fibrous cartilage tissue.

Hyaline cartilage

characterized by the presence of only collagen fibers in the intercellular substance. In this case, the refractive index of the fibers and the amorphous substance is the same and therefore fibers in the intercellular substance are not visible on histological preparations. This also explains the certain transparency of the cartilage, consisting of hyaline cartilage tissue. Chondrocytes in isogenic groups of hyaline cartilage tissue are arranged in the form of rosettes. According to its physical properties, hyaline cartilage tissue is characterized by transparency, density and low elasticity. In the human body, hyaline cartilage tissue is widespread and is part of the large cartilage of the larynx (thyroid and cricoid), trachea and large bronchi, makes up the cartilaginous parts of the ribs, covers the articular surfaces of the bones. In addition, almost all bones of the body pass through the stage of hyaline cartilage during their development.

Elastic cartilage tissue

characterized by the presence in the intercellular substance of both collagen and elastic fibers. In this case, the refractive index of elastic fibers differs from the refraction of an amorphous substance and therefore elastic fibers are clearly visible in histological preparations. Chondrocytes in isogenic groups in elastic tissue are arranged in columns or columns. According to its physical properties, elastic cartilage tissue is opaque, elastic, less dense and less transparent than hyaline cartilage tissue. It is part of elastic cartilage: auricle and cartilaginous part of the external auditory canal, cartilage of the external nose, small cartilage of the larynx and middle bronchi, and also forms the basis of the epiglottis.

Fibrous cartilage

characterized by the content in the intercellular substance of powerful bundles of parallel collagen fibers. In this case, chondrocytes are located between the fiber bundles in the form of chains. Its physical properties are characterized by high strength. It occurs in the body only in limited places: it forms part of the intervertebral discs (annulus fibrosus), and is also localized at the points of attachment of ligaments and tendons to hyaline cartilage. In these cases, a gradual transition of connective tissue fibrocytes to cartilage chondrocytes is clearly traced.

There are two concepts that should not be confused - cartilage tissue and cartilage. Cartilage tissue - This is a type of connective tissue, the structure of which is described above. Cartilageis an anatomical organ that consists of cartilage tissue and perichondrium.

Perichondrium

The perichondrium covers the cartilaginous tissue from the outside (with the exception of the cartilage tissue of the articular surfaces) and consists of fibrous connective tissue.

Two layers are distinguished in the perichondrium:

external - fibrous;

internal - cellular or cambial (germ).

In the inner layer, poorly differentiated cells are localized - prechondroblasts and inactive chondroblasts, which, in the process of embryonic and regenerative histogenesis, transform first into chondroblasts and then into chondrocytes. The fibrous layer contains a network of blood vessels. Consequently, the perichondrium, as an integral part of the cartilage, performs the following functions: provides the avascular cartilage tissue with trophism; protects cartilage tissue; ensures the regeneration of cartilage tissue when damaged.