Observation of the changes in the cartilage matrix in endochondral ossification of the rat mandibular condyle

Abstract

The changes in the crystals, matrix fibers and glycosaminoglycans of the calcified cartilage in the region where there is endochondral ossification in the 3-weeks-old rat mandibular Chondyle were observed by light and electron microscopy.The results are as follows:1. Most of the uncalcified collagen fibrils disappear when the cartilage lacunae open into the bone marrow cavity. But part of the collagen fibrils are burned in the bone matrix when the bone tissue is formed on the surface of the calcified cartilage.2. In the region of endochondral ossification the mineralization of the calcified cartilage matrix progresses slowly even after it is surrounded by a new bone tissue, also simultaneously the organic matrix consisting of the calcified cartilage is reduced relatively.3. When the bone tissues are formed on the surface of the calcified cartilage matrix, it seems that the initial crystal deposition appear on the surface of the calcified cartilage matrix and then on the collagen fibrils.