Cartilage

Two cartilagineux territories

the territorial substance , or chondroïque sphere , indicating the cellular part of the cartilage. The cells can be isolated or form small groups isogenic, i.e. resulting from divisions of a chondrocyte already isolated. Progressive insulation is due to the production on all the surface of the chondroblastes (the cells precursors which, once isolated, or into small groups isogenic, is called chondrocytes) extracellular matrix.
the intercellular substance , or cartilagineuse matrix , produced by the chondrocytes. It is the part acellulaire cartilage, consisted of glycosaminoglycanes, collagen (fibers of the type I, and type II), of chondronectine, fibromoduline, etc

The intercellular substance located near the chondroblastes has property Basophile S, it is the capsule . It is rich in chondroïtine 4-sulfate , in chondroïtine 6-sulfate , kératane sulfate , but low in collagen.

Various types of cartilages

The hyaline cartilage

Composition, activity of the chondrocyte

The chondrocytes are bulky, and the abundant extracellular matrix. The fibers of Collagenous II and XI form a network with broad meshs, invisible with the photonic microsope. Vascularization and the innervation are non-existent: the chondrocyte is nourished by imbibition starting from the bone under chondral. The Chondrocyte secret molecules of the intercellular substance, the cytokines, the enzymes able to degrade the matrix. They present hormonal receivers to growth hormones hypophyseal, the Thyroxine, the Testostérone and others sex hormones. At the adulthood, there is no more regeneration of the cartilage, thus any anomaly will be irreversible.

Localization

At the Adult man , there exist various types of hyaline cartilages.

The articular hyaline cartilage

It is found:

on the surface of the mobile articulations of synovial type (with a synovial capsule) in continuity of the Périoste of the bone.

The nonarticular hyaline cartilage

One finds it in:

the nasal partition separating both nasal fossae.
the cartilages thyroid, cricoïde and aryténoïdes of the Larynx.
rings of the grosses bronchi and the Trachea.
the end of the coasts as well as the two floating ribs.

With the birth, some Os are partly made up of this type of cartilage. Then, progressively by the years, its proportion in the bone decreases; with the Puberté there remain nothing any more but the cartilages of conjugation on the level of the long bones. Those will disappear at the end from the growth.

The fibrous cartilage or fibrocartilage

It is rich in collagen fibers, forming a screen visible with the photonic microscope. This structure makes it very resistant to tractions.

One can quote several examples of them:

the intervertebral discs of the Spinal column.
the pubic Symphyse between the two iliaque Os S.
the Meniscus S of the knees.

The elastic cartilage

It is rich in elastic fibers.

function: the form of a structure maintains by conferring a great flexibility to him.

One finds it on the level:

of the external Ear (house and external auditory canal).
of the Eustachian tubes.
of the épiglotte.

It presents a yellowish coloring which is due to the important presence of fiber rubber bands. (It is also rich in fibers of Collagène II.)

Osteogenesis enchondrale

Process

It can happen that the cartilagineux fabric serf of model at making of a bone tissue. In this case, the cartilagineuse model is reabsorbed (one speaks about cartilagineuse erosion) and is replaced by bone tissue; it is the Ossification endochondrale.

The cartilage of conjugation

It is hyaline cartilage located between the Métaphyse and the épiphyse of the bone ensuring the growth in length of this one. It disappears at the end of the growth.

Simple: Cartilage

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