CARTILAGE BAGIAN HISTOLOGIFAKULTAS KEDOKTERANUNIVERSITAS SRIWIJAYA2011YAN EFFEDI HASJIM

cells called chondrocytes, in small cavities (lacunae)extracellular matrix. No vascularized, no supplied nerves or lymphatic vessels; cells receive their nourishment from blood vessels of surrounding connective tissues by diffusion through the matrix. The extracellular matrix : glycosaminoglycans & proteoglycans, associated with the collagen and elastic fibers within lamella architecture. The flexibility and resistance to compression function as a shock absorber, smooth surface permits almost friction-free movement of the joints of the body as it covers the articulating surfaces of the bones.

The perichondriumconnective tissue sheath covering most cartilage. outer fibrous layer, inner cellular layer (cells secrete matrix). vascular, supply nutrients to the cells of cartilage. In areas where the cartilage has no perichondrium (e.g., the articular surfaces of the bones forming a joint), the cartilage cells receive their nourishment from the synovial fluid. present in elastic, most hyaline cartilages, but absent in fibrocartilage.

There are three types of cartilage (the fibers present in the matrix)Hyaline cartilage contains type II collagen in its matrix; most abundant cartilage in the body Elastic cartilage contains type II collagen and abundant elastic fibers giving it more pliability. Fibrocartilage dense, coarse type I collagen fibers in its matrix, withstand strong tensile forces.

Cartilage Cells (Three types) Chondrogenic spindle-shaped, are derived from mesenchymal cells. can differentiate into both chondroblasts and osteoprogenitor cells. Chondroblasts derived from two sources: mesenchymal cells (within the center of chondrification) and chondrogenic cells (inner cellular layer of the perichondrium) (as in appositional growth). Chondroblasts, basophilic, for protein synthesis. abundance of secretory vesicles.

Matrix of Hyaline Cartilage The matrix of hyaline cartilage is composed of type II collagen 40% dry weight), proteoglycans, glycoproteins, and extracellular fluid. two regions: The territorial matrix, poor in collagen and rich in chondroitin sulfate, contributes to its basophilic interterritorial matrix, richer in type II collagen and poorer in proteoglycans (than the territorial) pericellular capsule .A small region of the matrix, surrounding the

Histophysiology of Hyaline Cartilage

The smoothness of hyaline cartilage and its ability to resist forces of both compression and tension essential to articular surfaces of joints. Because cartilage is avascular, nutrients and oxygen must diffuse through the water of hydration present in the matrix. The inefficiency of such a system necessitates a limit on the width of cartilage. (changes with age). Hormones and vitamins also exert influence on the growth, development, and function of cartilage. skeletal formation and growth

CLINICAL CORRELATIONSHyaline cartilage degenerates when the chondrocytes hypertrophy, die and the matrix begins to calcify. This process is a normal and integral part of endochondral bone formation; it is also a natural process of aging, often resulting in less mobility and in joint pain.Cartilage regeneration is usually poor (except in children). Chondrogenic cells from the perichondrium enter the defect and form new cartilage. If the defect is large, the cells form dense connective tissue to repair the scar.

Elastic Cartilage Elastic cartilage greatly resembles hyaline cartilage, except that its matrix and perichondrium possess elastic fibers. Structure identical to hyaline cartilage The outer fibrous layer of the perichondrium is rich in elastic fibers. The matrix abundant, fine to coarse branching elastic fibers interposed with type II collagen fiber bundles, more flexibility than the matrix of hyaline cartilageThe chondrocytes more abundant and larger (than hyaline). the elastic fiber bundles of the territorial matrix are larger and coarser than interterritorial matrix.

Fibrocartilage intervertebral disks, pubic symphysis, articular disks, and attached to bone. Unlike the other, does not possess a perichondrium. rich in chondroitin sulfate and dermatan sulfatexhibits bundles of type I collagen, which stain acidophilic Chondrocytes are parallel rows with the thick, coarse bundles of collagen, which parallel the tensile forces attendant on this tissue

Intervertebral disks They are interposed between the hyaline cartilage coverings of the articular surface of successive vertebrae. Each disk contains a gelatinous center (nucleus pulposus), which is composed of cells, derived from the notochord, lying within a hyaluronic acid-rich matrix. These cells disappear by the 20th year of life. annulus fibrosus surrounding the nucleus pulposus, layers of fibrocartilage whose type I collagen fibers run vertically between the hyaline cartilages of the two vertebrae. The fibers of lamellae are oriented obliquely to each other, support to the gelatinous nucleus pulposus. The annulus fibrosus provides resistance against tensile forces, whereas the nucleus pulposus resists forces of compression.

CLINICAL CORRELATIONSA ruptured disk refers to a tear or break in the laminae of the annulus fibrosus the gel-like nucleus pulposus extrudes. often on the posterior portions of the intervertebral disks, particularly in the lumbar portion of the back, where the disk may dislocate, or slip ("slipped disk) severe, intense pain in the lower back and extremities, (the displaced disk compresses the lower spinal nerves).

Growth of CartilageInterstitial GrowthCells responsible for hyaline cartilage formation differentiate from mesenchymal cells. individual mesenchymal cells retract their processes, round up, and congregate in dense masses called chondrification centers. cells differentiate into chondroblasts, secreting cartilage matrix around themselves. As this process continues, the chondroblasts become entrapped in their own matrix in lacunae. These cells are still capable of cell division, forming a cluster of two to four or more cells in a lacuna. These groups are known as isogenous interstitial growth.

Appositional Growth. (grows by adding to its periphery)Mesenchymal cells at the periphery of the developing cartilage differentiate to fibroblasts. perichondrium The perichondrium has two layers, an outer fibrous layer composed of type I collagen, fibroblasts, and blood vessels and an inner cellular layer composed mostly of chondrogenic cells. The chondrogenic cells division and differentiate into chondroblasts, which begin to elaborate matrix.

Unique Features of CartilageArticulatingCartilage

SUKSES UNTUK MUAMIIIN, TERIMA KASIH