Cartilage

Cartilage, tough, flexible connective tissue found in all vertebrates, consisting of cartilage cells in a matrix of collagen fibers and a firm protein gel. The skeleton of the vertebrate embryo is formed wholly of cartilage; in most species much of this is replaced by bone during growth. There are 3 main types of cartilage: (1) hyaline, which is translucent and glossy and found in the joints, nose, trachea, and bronchi; (2) elastic, which is found in the external ear, Eustachian tube, and larynx; and (3) fibrocartilage, which attaches tendons to bone and forms the disks between the vertebrae.

See also: Bone.