Elastic cartilage is characterised by the presence of elastic fibres within the matrix which increase elasticity in tissues such as the external ear and trachea. Physeal cartilage provides longitudinal growth to immature long bones. Chondroblasts which are derived from mesenchymal cells become trapped in lacunae and develop into chondrocytes. Articular cartilage is a highly hydrated material. Weight bearing capacity is made possible through regional changes in water content which allow deformation of the cartilage surface in response to stress.
Water provides nutrition and lubrication of cartilage.
GAG's are bound to a protein core by sugar bonds to form a proteoglycan aggrecan molecule. Aggrecan molecules are further stabilised by link proteins which bind them to hyaluronic acid to form a proteoglycan aggregate. Lipids are present in cartilage but their function is unknown. Calcified Zone Hydroxyapatite crystals anchor the cartilage to the subchondral bone. Metabolism Collagen Synthesis of collagen takes place in stages at various intracellular and extracellular sites.