hyaline cartilage

hyaline cartilage, type of connective tissue, glossy pearl-gray or blue-white in appearance and resilient, found on surfaces of joints and in the cartilage making up the fetal skeleton. In human adults, hyaline cartilage persists at the ends of bones in free-moving joints as articular cartilage, at the ends of the ribs, and in the nose, larynx, trachea, and bronchi. The deformable but elastic qualities of hyaline cartilage are important for its function within joints, where it recovers its shape quickly after the deforming stress accompanied by absorption of compressive shock is removed. Hyaline cartilage, the most widespread type of cartilage in the body, is one of three types of cartilage, the other two being elastic cartilage and fibrocartilage.

The semitranslucent matrix of hyaline cartilage contains randomly oriented collagen fibrils and cells known as chondrocytes. It is devoid of blood vessels and nerves. Although avascular, gaseous metabolites and nutrients can diffuse through the aqueous phase of the gel-like matrix to reach the cells. Articular cartilage is largely dependent upon the synovial fluid of the joint for its nourishment (see synovial tissue).

Hyaline cartilage is enclosed by a perichondrium, a dense fibrous layer lined by cells that have the capacity to secrete hyaline matrix. Cartilage grows by formation of additional matrix and incorporation of new cells from the inner chondrogenic layer of the perichondrium. In addition, young chondrocytes retain the capacity to divide even after they become isolated in lacunae within the matrix. The daughter cells of these divisions secrete new matrix between them and move apart in separate lacunae. The capacity of cartilage for both appositional and interstitial growth makes it a favourable material for the skeleton of the rapidly growing embryo. The cartilaginous skeletal elements present in fetal life are subsequently replaced by bone.

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