Scanning electron microscopy of mineralized cartilage in rat mandibular condyle.

The pattern of mineralization was studied in the mandibular condyle of the young adult rat. Specimens were rendered anorganic in NaOC1 and examined in a scanning electron microscope. A mineralized cartilage front was found to persist on the articular aspect of the condyle. The surface is characterized by closely approximating chondrocyte lacunae enclosed to different degrees within the mineralized front. The mineralized component itself is calcospheritic; larger calcospherites forming the inner concave wall and smaller calcospherites forming the outer convex wall. The calcospherites are comprised of irregular crystalline plates radiating from the center of the mass. The bony surface of the ramus immediately beneath the condyle is typified by Howship's lacunae alternating with areas of forming bone indicating intense remodeling activity. The mandibular condyle has not been examined in this way before. The information is relevant to consideration of growth and development, functional adaptation, physiological aging, and pathological change.