This appears as a bluish-white translucent mass when fresh. It forms the articular cartilage of joints, the costal cartilages and cartilages of nose, larynx trachea and bronchi.
In the foetus nearly the entire skeleton is first laid down as hyaline cartilage and later replaced by osseous tissue in the formation of bone. The tissue is organized into plate like masses which with the exception of articular cartilages, are invested by a fibrous membrane, the perichondrium.
Each plate consists of cells and a homogenous matrix, the connective tissue fibrils being masked by ground substance. There is neither blood supply nor nerve supply for the cartilage.
Cartilage cells (chondrocytes) are situated in smooth-walled spaces or lacunae. Each cell has a large central spherical nucleus with one or more nucleoli. The cytoplasm is finely granular and contains fat, glycogen and occasionally pigment.
In life the cells fill up the lacunae, but after fixation in ordinary methods, fat and glycogen are dissolved and the shrunken cells are separated by spaces from the walls of the lacunae, give the cells a branched appearance.
In the centre of the mass the cells are arranged in isogenous groups, each group representing the offspring of one parent cartilage cell. The cells are spherical or ovoid, flattened on adjacent sides, their long axes directed radially towards the surface of the plate, towards the periphery, cells become flattened loose their definite grouping until in the subperichondrial layers they appear as rows of narrow elongated cells with their long axes parallel to the surface. Cartilage here merges insensibly with the fibrous connective tissue of the perichondrium.
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