cartilage tissue is a type of hard connective tissue. From the name it is clear that it consists of cartilage cells and intercellular substance. The main function of cartilage tissue is support.
Cartilage tissue has high elasticity and elasticity. For joints, cartilage is very important - it eliminates friction due to the release of fluid and lubrication of the joints. Due to this, the load on the joints is significantly reduced.
Unfortunately, with age, cartilage tissue loses its properties. Often cartilage tissue is damaged and in young age. This is because cartilage is very prone to destruction. It is very important to take care of your health in time, since damaged cartilage tissue is one of the main causes of diseases of the musculoskeletal system.
Types of cartilage
- hyaline cartilage
- Elastic cartilage
- fibrocartilage
hyaline cartilage tissue found in the composition of the cartilage of the larynx, bronchi, bone temafises, in the area of attachment of the ribs to the sternum.
Made from elastic cartilage consist of auricles, bronchi, larynx.
Fibrous cartilage tissue is located in the area of transition of ligaments and tendons to hyaline cartilage tissue.
However, all three types of cartilage tissue are similar in composition - they consist of cells (chondrocytes) and intercellular substance. The latter has a high bypass, approximately 60-80 percent of water. In addition, the intercellular substance occupies more space than cells. The chemical composition is quite complex. The intercellular substance of the cartilaginous tissue is divided into an amorphous substance and a fibrillar component, which includes about forty percent of the dry matter - collagen. The production of the matrix (intercellular substance) is carried out by chondroblasts and young chondrocytes.
Chondroblasts and chondrocytes
Chondroblasts are round or ovoid cells. The main task: the production of components of the intercellular substance, such as collagen, elastin, glycoproteins, proteoglycans.
Chondrocytes take into account mature cells of cartilage tissue of large size. The shape can be round, oval, polygonal. Where are chondrocytes located? In lacunae. The intercellular substance surrounds chondrocytes. The walls of the lacunae are two layers - the outer one (made of collagen fibers) and the inner one (made of proteoglycan aggregates).
It combines not only collagen fibrils, but also elastic fibers, which consist of elastin protein. Its production is also the task of cartilage cells. Elastic cartilage tissue is characterized by increased flexibility.
The composition of fibrous cartilage tissue includes bundles of collagen fibers. Fibrous cartilage is very strong. Fibrous rings of intervertebral discs, intra-articular discs consist of fibrous cartilage tissue. In addition, fibrous cartilage covers the articular surfaces of the temporomandibular and sternoclavicular joints.
36. Skeletal tissues. general characteristics. Cartilaginous tissues, localization in the body. Cellular composition, features of the organization of the intercellular substance in different types cartilage. Structural and functional characteristics of cells and intercellular substance. The concept of an isogenic group of cells.
Skeletalfabrics
GeneralcharacteristicboneAndcartilaginousfabrics
Skeletal tissues (textus skeletales) are a type of connective tissue with a pronounced supporting, mechanical function due to the presence of a dense intercellular substance. Skeletal tissues include:
cartilaginousfabrics,
bonefabrics,
dentinetooth
cementtooth.
In addition to the main supporting function, these tissues are involved in water-salt metabolism, mainly calcium and phosphate salts.
Like all other tissues of the internal environment of the body, skeletal tissues develop from the mesenchyme, - more precisely, from the mesenchyme that is evicted from the sclerotomes of the mesoderm.
cartilaginousfabrics
Cartilaginous tissues (textus cartilaginei) are distinguished by their elasticity and strength, which is associated with the position of this tissue in the body. Cartilage tissue is part of the organs of the respiratory system, joints, intervertebral discs.
As in other tissues, cells and intercellular substance are isolated in cartilage tissue. The main cellular elements are chondroblasts and chondrocytes. There is more intercellular substance in cartilage tissue than cells. It is hydrophilic and elastic. It is with the elasticity of the intercellular substance that the supporting function of cartilage tissues is associated.
Cartilage tissue is significantly hydrated - fresh tissue contains up to 80% water. More than half of the volume of the "dry" substance of the cartilage tissue is the fibrillar protein collagen. There are no vessels in the cartilage tissue - nutrients diffuse from the surrounding tissues.
Classification
Distinguishthreekindcartilaginousfabrics:
hyaline,
elastic,
fibrous.
Such a subdivision of cartilage tissues is based on the structural and functional features of the structure of their intercellular substance, the degree of content and ratio of collagen and elastic fibers.
Briefcharacteristiccellscartilaginousfabrics
Chondroblasts are small flattened cells capable of dividing and synthesizing intercellular substance. By releasing the components of the intercellular substance, chodroblasts, as it were, "immure" themselves in it - they turn into chondrocytes. The cartilage growth that occurs in this case is called peripheral, or appositional, i.e. by "imposing" new layers of cartilage.
Chondrocytes are larger and oval in shape. They lie in special cavities of the intercellular substance - lacunae. Chondrocytes often form the so-called. isogenic groups of 2-6 cells that originated from a single cell. At the same time, some chondrocytes retain the ability to divide, while others actively synthesize components of the intercellular substance. Due to the activity of chondrocytes, an increase in the mass of cartilage from the inside occurs - interstitial growth.
types of cartilage tissue, age-related changes and cartilage regeneration
Based on the structural features of the intercellular substance, cartilage tissues are divided into three types - hyaline, elastic and fibrous, or fibrous.
hyaline cartilage tissue
Hyaline cartilage tissue (textus cartilaginous hyalinus), also called vitreous (from the Greek hyalos - glass) - due to its transparency and bluish-white color, is the most common type of cartilage tissue. In an adult organism, hyaline tissue is found on the articular surfaces of bones, at the junction of the ribs with the sternum, in the larynx and airways.
Most of the hyaline cartilage tissue found in the human body is covered with the perichondrium (perichondrium) and, together with the plate of cartilage tissue, is anatomical formations - cartilage.
In the perichondrium, two layers are distinguished: the outer one, consisting of fibrous connective tissue with blood vessels; and internal, predominantly cellular, containing chondroblasts and their precursors - prechondroblasts. Under the perichondrium in the surface layer of the cartilage are young chondrocytes of a spindle-shaped flattened shape. In the deeper layers, cartilage cells acquire an oval or rounded shape. Due to the fact that the synthetic and secretory processes in these cells are weakened, after division they do not diverge far, but lie compactly, forming isogenic groups from 2 to 4 (rarely up to 6) chondrocytes.
Elastic cartilage tissue
The second type of cartilage tissue - elastic cartilage tissue (textus cartilagineus elasticus) is found in those organs where the cartilaginous base is subjected to bends (in the auricle, carob-shaped and wedge-shaped cartilages of the larynx, etc.). In a fresh, unfixed state, elastic cartilage is yellowish in color and not as transparent as hyaline. According to the general plan of the structure, the elastic cartilage is similar to hyaline. Outside, it is covered with a perichondrium. Cartilage cells (young and specialized chondrocytes) are located in lacunae singly or form isogenic groups.
One of the main distinguishing features of elastic cartilage is the presence of elastic fibers in its intercellular substance, along with collagen fibers. Elastic fibers penetrate the intercellular substance in all directions.
In the layers adjacent to the perichondrium, the elastic fibers pass without interruption into the elastic fibers of the perichondrium. There are less lipids, glycogen and chondroitin sulfates in the elastic cartilage than in hyaline.
Fibrous cartilage tissue
The third type of cartilage tissue - fibrous, or fibrous, cartilaginous tissue (textus cartilaginous fibrosa) is located in intervertebral discs, semi-movable joints, at the transition points of dense fibrous connective tissue of tendons and ligaments into hyaline cartilage, where limited movements are accompanied by strong tensions. The intercellular substance contains parallel directed collagen bundles, gradually loosening and passing into hyaline cartilage. Cartilage contains cavities that contain cartilage cells. Chondrocytes are located singly or form small isogenic groups. The cytoplasm of cells is often vacuolated. In the direction from the hyaline cartilage to the tendon, the fibrocartilage becomes more and more like a tendon. On the border of the cartilage and the tendon between the collagen bundles, compressed cartilage cells lie in columns, which, without any border, pass into the tendon cells located in the dense, formed fibrous connective tissue of the tendon.
Age changes and regeneration
As the body ages, the concentration of proteoglycans in the cartilage tissue and the associated tissue hydrophilicity decrease. The processes of reproduction of chondroblasts and young chondrocytes are weakened.
Chondroclasts participate in the resorption of dystrophically altered cells and intercellular substance. Some of the gaps after the death of chondrocytes are filled with an amorphous substance and collagen fibrils. In places, deposits of calcium salts are found in the intercellular substance (“shallowening of the cartilage”), as a result of which the cartilage becomes cloudy, opaque, becomes hard and brittle. As a result, the resulting violation of the trophism of the central sections of the cartilage can lead to the ingrowth of blood vessels into them, followed by bone formation.
Physiological regeneration of cartilage tissue is carried out at the expense of little specialized cells of the perichondrium and cartilage through the reproduction and differentiation of prechondroblasts and chondroblasts. However, this process is very slow. Post-traumatic regeneration of cartilaginous tissue of extra-articular localization is carried out at the expense of the perichondrium. Recovery can occur due to the cells of the surrounding connective tissue that have not lost their ability to metaplasia (i.e., the transformation of fibroblasts into chondroblasts).
In the articular cartilage, depending on the depth of the injury, regeneration occurs both due to the multiplication of cells in isogenic groups (in case of shallow damage) and due to the second source of regeneration - cambial cells of subchondral bone tissue (in case of deep cartilage damage).
cartilage tissue, like bone, refers to skeletal tissues with a musculoskeletal function. According to the classification, three types of cartilage tissue are distinguished - hyaline, elastic and fibrous. Structural features various kinds cartilage depends on its location in the body, mechanical conditions, the age of the individual.
Types of cartilage tissue: 1 - hyaline cartilage; 2 - elastic cartilage; 3 - fibrous cartilage
The most widespread in humans ishyaline cartilage tissue.
It is part of the trachea, some cartilages of the larynx, large bronchi, temaphyses of bones, is found at the junction of the ribs with the sternum and in some other areas of the body. Elastic cartilage tissue is part of the auricle, medium-sized bronchi, and some cartilages of the larynx. Fibrous cartilage is commonly found at the junction of tendons and ligaments with hyaline cartilage, such as intervertebral discs.
The structure of all types of cartilage in in general terms similar: they contain cells and an intercellular substance (matrix). One of the features of the intercellular substance of the cartilaginous tissue is its high water content: the water content normally ranges from 60 to 80%. The area occupied by the intercellular substance more area occupied by cells. The intercellular substance of cartilage tissue is produced by cells (chondroblasts and young chondrocytes) and has a complex chemical composition. It is subdivided into the main amorphous substance and the fibrillar component, which makes up approximately 40% of the dry mass of the intercellular substance and is represented in the hyaline cartilage tissue by collagen fibrils formed by type II collagen, which diffuse in different directions. On histological preparations, fibrils are invisible, since they have the same refractive index as an amorphous substance. In the elastic cartilage tissue, along with collagen fibrils, there are numerous elastic fibers consisting of elastin protein, which is also produced by cartilage cells. Fibrous cartilage contains a large number of bundles of collagen fibers, consisting of type I and type II collagen.
Leading chemical compounds, which form the main amorphous substance of cartilaginous tissues (chondromucoid), are sulfated glycosaminoglycans (keratosulfates and chondroitin sulfates A and C) and neutral mucopolysaccharides, most of which are complex supramolecular complexes. In cartilage, compounds of hyaluronic acid molecules with proteoglycans and with specific sulfated glycosaminoglycans have become widespread. This ensures special properties cartilage tissue - mechanical strength and at the same time permeable to organic compounds, water and other substances necessary to ensure the vital activity of cellular elements. The marker compounds most specific for the intercellular substance of cartilage are keratosulfates and certain varieties of chondroitin sulfates. They make up about 30% of the dry mass of cartilage.
The main cells of cartilage tissue -chondroblasts and chondrocytes.
Chondroblastsare young, undifferentiated cells. They are located near the perichondrium, lie singly and are characterized by a round or oval shape with uneven edges. A large nucleus occupies a significant part of the cytoplasm. Synthesis organelles predominate among cell organelles - ribosomes and polysomes, granular endoplasmic reticulum, Golgi complex, mitochondria; characterized by inclusions of glycogen. With general histological staining of preparations with hematoxylin and eosin, chondroblasts are weakly basophilic. The structure of chondroblasts indicates that these cells show high metabolic activity, in particular, associated with the synthesis of intercellular substance. It has been shown that in chondroblasts the synthesis of collagen and non-collagen proteins is spatially separated. The entire cycle of synthesis and excretion of high-molecular components of the intercellular substance in functionally active human chondroblasts takes less than a day. Newly formed proteins, proteoglycans and glycosaminoglycans are not located directly near the cell surface, but spread diffusely at a considerable distance from the cell in the previously formed intercellular substance. Among chondroblasts, there are also functionally inactive cells, the structure of which is characterized by a weak development of the synthetic apparatus. In addition, part of the chondroblasts located immediately under the perichondrium did not lose the ability to divide.
Chondrocytes- Mature cells of cartilage tissue - occupy mainly the central parts of the cartilage. The synthetic ability of these cells is significantly lower than that of chondroblasts. Differentiated chondrocytes most often lie in cartilaginous tissues not singly, but in groups of 2, 4, 8 cells. These are the so-called isogenic groups of cells, which were formed as a result of the division of one cartilage cell. The structure of mature chondrocytes indicates that they are not capable of division and a noticeable synthesis of intercellular substance. But some researchers believe that under certain conditions, mitotic activity in these cells is still possible. The function of chondrocytes is to maintain at a certain level of metabolic metabolic processes in cartilage tissues.
Isogenic groups of cells are located in cartilaginous cavities surrounded by a matrix. The shape of cartilage cells in isogenic groups can be different - round, oval, fusiform, triangular - depending on the position on a particular area of cartilage. The cartilaginous cavities are surrounded by a narrow, lighter than the main substance, strip, forming, as it were, a shell of the cartilaginous cavity. This shell, which is characterized by oxyphilicity, is called the cellular territory, or territorial matrix. The more distant regions of the intercellular substance are called the interstitial matrix. Territorial and interstitial matrices are areas of intercellular substance with different structural and functional properties. Within the territorial matrix, collagen fibrils are oriented around the surface of isogenic cell groups. Weaves of collagen fibrils form a wall of lacunae. The spaces between cells within the lacunae are filled with proteoglycans. The interstitial matrix is characterized by weakly basophilic or oxyphilic coloration and corresponds to the oldest sections of the intercellular substance.
Thus, the definitive cartilage tissue is characterized by a strictly polarized distribution of cells depending on the degree of their differentiation. Near the perichondrium are the least differentiated cells - chondroblasts, which look like cells elongated parallel to the perichondrium. They actively synthesize the intercellular substance and retain the mitotic ability. The closer to the center of the cartilage, the more differentiated the cells are, they are located in isogenic groups and are characterized by a sharp decrease in the synthesis of components of the intercellular substance and the absence of mitotic activity.
In modern scientific literature, another type of cartilage tissue cells is described -chondroclasts. They occur only during the destruction of cartilaginous tissue, and in the conditions of its normal life are not detected. In size, chondroclasts are much larger than chondrocytes and chondroblasts, since they contain several nuclei in the cytoplasm. The function of chondroclasts is associated with the activation of cartilage degeneration processes and participation in phagocytosis and lysis of fragments of destroyed cartilage cells and cartilage matrix components. In other words, chondroclasts are macrophages of cartilaginous tissue that are part of a single macrophage-phagocytic system of the body.
Joint diseases
IN AND. Mazurov
It is no secret that athletes, even in good physical shape and relatively early age often drop out of training due to injury. A large proportion of their problems are ligaments. Their weakest part is cartilage tissue. It turns out that the functions of damaged joints can be restored if you pay attention to the problem in time and create suitable conditions for the treatment and regeneration of their cells.
Tissues in the human body
The human body is a complex and flexible system capable of self-regulation. It consists of cells of various structures and functions. They carry out the main metabolism. Together with non-cellular structures, they are combined into tissues: epithelial, muscle, nervous, connective.
Epithelial cells form the basis skin. They line internal cavities(abdominal, thoracic, upper respiratory tract, intestinal tract). Muscle tissue allows a person to move. It also ensures the movement of internal media in all organs and systems. The muscles are divided into types: smooth (walls of abdominal organs and vessels), cardiac, skeletal (striated). Nervous tissue provides the transmission of impulses from the brain. Some cells are able to grow and multiply, some of them are capable of regeneration.
Connective tissue is internal environment organism. It is different in structure, structure and properties. It consists of strong bones of the skeleton, subcutaneous fatty tissue, liquid media: blood and lymph. It also includes cartilage. Its functions are forming, cushioning, supporting and supporting. All of them play an important role and are necessary in complex system organism.
structure and functions
Her characteristic- looseness in the arrangement of cells. Looking at them individually, you can see how clearly they are separated from each other. The bond between them is the intercellular substance - the matrix. Moreover, in different types of cartilage, it is formed, in addition to the main amorphous substance, by various fibers (elastic and collagen). Although they have a common protein origin, they differ in properties and, depending on this, perform different functions.
All bones in the body are made up of cartilage. But as they grew, their intercellular substance was filled with salt crystals (mainly calcium). As a result, the bones gained strength and became part of the skeleton. Cartilages also perform supporting functions. In the spine, being between the segments, they perceive constant loads (static and dynamic). The auricles, nose, trachea, bronchi - in these areas, the tissue plays a more formative role.
The growth and nutrition of the cartilage is carried out through the perichondrium. It is an obligatory part in the tissue, except for the joints. They contain synovial fluid between the rubbing surfaces. It washes, lubricates and nourishes them, removes metabolic products.
Structure
There are few cells in the cartilage capable of dividing, and there is a lot of space around them, filled with a protein substance of various properties. Because of this feature, regeneration processes often take place in the matrix to a greater extent.
There are two types of tissue cells: chondrocytes (mature) and chondroblasts (young). They differ in size, location and method of location. Chondrocytes are round and larger. Arranged in pairs or in groups of up to 10 cells. Chondroblasts are usually smaller and are located in the tissue along the periphery or singly.
In the cytoplasm of cells under the membrane, water accumulates, there are inclusions of glycogen. Oxygen and nutrients diffuse into cells. There is a synthesis of collagen and elastin. They are necessary for the formation of intercellular substance. It depends on its specificity what type of cartilage tissue it will be. Structural features and differ from intervertebral discs, including the content of collagen. In the cartilage of the nose, the intercellular substance consists of 30% elastin.
Kinds
How it is classified Its functions depend on the predominance of specific fibers in the matrix. If there is more elastin in the intercellular substance, then the cartilage tissue will be more plastic. It is almost as strong, but the fiber bundles in it are thinner. They well withstand loads not only in compression, but also in tension, are capable of deformation without critical consequences. Such cartilage is called elastic. Their tissues form the larynx, auricles, nose.
If in the matrix around the cells great content collagen with a complex structure of building polypeptide chains, such cartilage is called hyaline. It most often covers the inner surfaces of the joints. The largest number collagen is concentrated in the superficial zone. It plays the role of a framework. The bundles of fibers in it are structurally reminiscent of three-dimensional intertwined networks of a spiral shape.
There is another group: fibrous, or fibrous, cartilage. They, like hyaline, contain a large amount of collagen in the intercellular substance, but it has a special structure. The bundles of their fibers do not have a complex weave and are located along the axis of the greatest loads. They are thicker, have a special compressive strength, and are poorly restored during deformation. Intervertebral discs, the junction of tendons with bones, are formed from such tissue.
Functions
Due to its special biomechanical properties, cartilage tissue is ideal for binding the components of the musculoskeletal system. It is able to accept the impact of compressive and tensile forces during movements, redistribute them evenly to the load, absorb or dissipate to some extent.
The cartilages form abrasion-resistant surfaces. In combination with synovial fluid, such joints with allowable loads able to perform their functions normally for a long time.
Tendons are not cartilage. Their functions also consist in linking into a common apparatus. They also consist of bundles of collagen fibers, but their structure and origin are different. respiratory organs, auricles, in addition to performing forming and supporting functions, are the place of attachment of soft tissues. But unlike tendons, the muscles next to them do not have such a load.
Special properties
There are very few vessels in elastic cartilage. And this is understandable, because a strong dynamic load can damage them. How is cartilage connective tissue fed? These functions are taken over by the intercellular substance. There are no vessels in hyaline cartilage at all. Their rubbing surfaces are quite hard and dense. They are powered by the synovial fluid of the joint.
In the matrix, water moves freely. It contains all the necessary substances for metabolic processes. The proteoglycan components in cartilage are ideal for binding water. As an incompressible substance, it provides rigidity and additional cushioning. When loaded, water takes on the impact, spreads throughout the intercellular space and smoothly relieves stress, preventing irreversible critical deformations.
Development
In the body of an adult, up to 2% of the mass falls on cartilage tissue. Where is it located and what functions does it perform? Cartilaginous and bone tissue in the embryonic period is not differentiated. Embryos have no bones. They develop from cartilage and are formed by the time of birth. But part of it never ossifies. Ears, nose, larynx, bronchi are formed from it. It is also present in the joints of the arms and legs, the joints of the intervertebral discs, the menisci of the knees.
Cartilage development occurs in several stages. First, the mesenchymal cells are saturated with water, round, lose their processes and begin to produce substances for the matrix. After that, they differentiate into chondrocytes and chondroblasts. The former are densely surrounded by intercellular substance. In this state, they can divide a limited number of times. After such processes, an isogenic group is formed. Cells remaining on the surface of the tissue become chondroblasts. In the process of producing matrix substances, final differentiation occurs, a structure is formed with a distinct division into a thin border and tissue base.
Age changes
Cartilage functions do not change during life. However, over time, signs of aging can be noticed: the muscles and tendons of the joints weaken, flexibility is lost, pain is disturbed by a change in the weather or with an unusual load. Such a process is considered a physiological norm. By the age of 30-40 years, the symptoms of changes may already begin to cause inconvenience to a greater or lesser extent. The aging of the articular cartilage tissue occurs due to the loss of its elasticity. The elasticity of the fibers is lost. The fabric dries up and loosens.
Cracks appear on a smooth surface, it becomes rough. Smoothness and ease of sliding is no longer possible. Damaged edges grow, deposits form in them, and osteophytes form in the tissue. Elastic cartilages age with the accumulation of calcium in the intercellular substance, but this almost does not affect their functions (nose, auricles).
Dysfunction of cartilage and bone tissue
When and how can this happen? To a large extent, it depends on what function the cartilage tissue performs. In the intervertebral discs, the main function of which is stabilizing and supporting, most often disruption occurs during the development of dystrophic or degenerative processes. The situation can lead to displacements, which, in turn, will lead to compression of the surrounding tissues. Swelling, pinching of nerves, squeezing of blood vessels is inevitable.
To restore stability, the body tries to fight the problem. The vertebra in the place of deformation “adjusts” to the situation, grows in the form of peculiar bone outgrowths (whiskers). This also does not benefit the surrounding tissues: again swelling, infringement, compression. This problem is complex. Violations of the functioning of the osteochondral apparatus are commonly called osteochondrosis.
Prolonged restriction of movement (gypsum for injuries) also negatively affects the cartilage. If, under excessive loads, elastic fibers degenerate into coarse fibrous bundles, then with low activity, cartilage ceases to eat normally. The synovial fluid does not mix well, chondrocytes receive less nutrients, as a result, they are not produced. required amount collagen and elastin for the matrix.
The conclusion suggests itself: for normal operation joint cartilage must receive sufficient tension and compression load. To ensure this, you need to exercise, lead a healthy and active image life.
In the human body, cartilage tissues serve as a support and connection between the structures of the skeleton. There are several types of cartilage structures, each of which has its own location and performs its tasks. Skeletal tissue undergoes pathological changes due to intense physical activity, congenital pathologies, age and other factors. To protect yourself from injuries and diseases, you need to take vitamins, calcium supplements and not be injured.
The value of cartilage structures
Articular cartilage holds skeletal bones, ligaments, muscles and tendons together into a single musculoskeletal system. It is this type of connective tissue that provides cushioning during movement, protecting the spine from damage, preventing fractures and bruises. The function of cartilage is to make the skeleton elastic, elastic and flexible. In addition, cartilage forms a supporting frame for many organs, protecting them from mechanical damage.
Features of the structure of cartilage tissue
The specific gravity of the matrix exceeds the total mass of all cells. Overall plan cartilage structure consists of 2 key elements: intercellular substance and cells. During the histological examination of the sample under the lenses of a microscope, the cells are located on a relatively smaller percentage of the area of space. The intercellular substance contains about 80% water in the composition. The structure of hyaline cartilage provides its main role in the growth and movement of the joints.
intercellular substance
The strength of cartilage is determined by its structure. The matrix, as an organ of cartilaginous tissue, is heterogeneous and contains up to 60% amorphous mass and 40% chondrin fibers. Fibrils histologically resemble human skin collagen, but differ in more chaotic placement. The ground substance of cartilage consists of protein complexes, glycosaminoglycans, hyaluronan compounds and mucopolysaccharides. These components provide durable cartilage properties, keeping it permeable to essential nutrients. There is a capsule, its name is perichondrium, it is a source of cartilage regeneration elements.
Cellular composition
Chondrocytes are located in the intercellular substance rather chaotically. The classification divides cells into undifferentiated chondroblasts and mature chondrocytes. The precursors are formed by the perichondrium, and as they move into deeper tissue balls, the cells differentiate. Chondroblasts produce matrix ingredients, which include proteins, proteoglycans, and glycosaminoglycans. Young cells by division provide interstitial growth of cartilage.
Chondrocytes located in deep tissue spheres are grouped by 3-9 cells, known as "isogenic groups". This mature cell type has a small nucleus. They do not divide, and their metabolic rate is greatly reduced. The isogenic group is covered by intertwined collagen fibers. The cells in this capsule are separated by protein molecules and have a variety of shapes.
With degenerative-dystrophic processes, multinucleated chondroclast cells appear, which destroy and absorb tissues.
The table presents the main differences in the structure of cartilage tissue types:
| View | Peculiarities |
|---|---|
| Hyaline | Thin collagen fibers |
| Has basophilic and oxyphilic zones | |
| elastic | Made up of elastin |
| Very flexible | |
| Has a cellular structure | |
| Fibrous | Formed from a large number collagen fibrils |
| Chondrocytes are comparatively larger | |
| Lasting | |
| Able to withstand high pressure and compression |
Blood supply and nerves
The tissue is not supplied with blood from its own vessels, but receives it by diffusion from adjacent ones. Due to the very dense structure, cartilage does not have blood vessels of even the smallest diameter. Oxygen and all the nutrients necessary for life and functioning come by diffusion from nearby arteries, perichondrium or bone, and are also extracted from the synovial fluid. Decay products are also excreted diffusely.
In the upper balls of the perichondrium there are only a small number of individual branches of nerve fibers. Thus, the nerve impulse is not formed and does not spread in pathologies. The localization of the pain syndrome is determined only when the disease destroys the bone, and the cartilage tissue structures in the joints are almost completely destroyed.
Varieties and functions
Depending on the type and relative position of fibrils, histology distinguishes the following types of cartilage tissue:
- hyaline;
- elastic;
- fibrous.
Each type is characterized by a certain level of elasticity, stability and density. The location of the cartilage determines its tasks. The main function of cartilage is to ensure the strength and stability of the joints of the parts of the skeleton. The smooth hyaline cartilage found in the joints makes it possible for the bones to move. Thanks to his appearance it is called vitreous. The physiological conformity of the surfaces guarantees a smooth glide. The structural features of hyaline cartilage and its thickness make it integral part ribs, upper rings respiratory tract.
The shape of the nose is formed by an elastic type of cartilage. Elastic cartilage forms appearance, voice, hearing and breathing. This applies to the structures that are in the skeleton of the bronchi of small and medium caliber, the auricles and the tip of the nose. The elements of the larynx are involved in the formation of a personal and unique voice timbre. Fibrous cartilage connects skeletal muscles, tendons, and ligaments to vitreous cartilage. Intervertebral and intra-articular discs and menisci are built from fibrous structures; they cover the temporomandibular and sternoclavicular joints.