Osteogenic Fronts Research Articles

Ossification in adult rat mandibular coyndyle—SEM of chondroclasia

The morphology of the mineralized component at the osteochondral junction was studied in the mandibular condyle of 264-day-old rats. Specimens were rendered anorganic in NaOCl, cut open with a sculpel, and the resulting surfaces examined in a scanning electron microscope. The extent of the mineralized cartilage plate and its relationship to invading vascular channels were visualized. Areas of resorption of calcified cartilage were identified and compared to areas of bone resorption. A likely sequence of events was reconstructed from the exposed internal surfaces: from initial chondroclasia in individual lacunae to extensive resorption of the cartilage plate; and from initial deposition of bone over the resorbed calcified cartilage cores to the organization of osteocyte lacunae and bony trabecule. The mandibular condyle has not been examined in this way previously. Possible cellular mechanisms suggested by other studies to be operating at the osteogenic front are discussed in the light of the results.