Functions of endothelium osteoclasts and hypertrophic chondrocytes in early phase of endochondral ossification

采用超微结构和组织化学方法对妊娠期16号黏土小鼠下颌髁软骨内成骨部位进行了初步研究。破骨细胞吸收骨领后，将其细胞突向软骨基质延伸，并与肥大软骨细胞接触。这些破骨细胞通过细胞过程或空泡结构包裹钙化软骨基质、细胞碎片和降解的未钙化软骨基质。因此，破骨细胞可能在不利用皱褶边界的情况下处理这些物质。而CD44被认为是透明质酸受体，在这些破骨细胞的细胞表面被广泛检测到。因此，破骨细胞和软骨透明质酸之间的相互作用被认为是在这个部位。侵袭的内皮也直接包围降解的未钙化软骨基质和少量细胞碎片沉积物。此外，附着在入侵的破骨细胞上的肥大软骨细胞经常包围小的钙化软骨基质。这些发现提示内皮细胞、破骨细胞和肥大软骨细胞在这一部位具有未知的独特功能。另一方面，我们利用这笔资金，对发育中的大鼠髁突软骨和牙髓进行了免疫组化研究，研究结果已发表或即将发表。

Ultrastructural and histochemical studies ware undertaken focused on the initial endochondral bone formation site in the mouse mandibular condyle of clay 16 of pregnancy. After resorbing the bone collar, the osteoclasts extended their cell processes into cartilage matrix and made contact with hypertrophic chondrocytes. By means of cell process or vacuolar structures, these osteoclasts entrapped the calcified cartilage matrices, cell debris, and the degraded uncalcified cartilage matrices. Thus, osteoclasts probably disposed of these substances without utilizing ruffled borders. While, CD44 that is considered as hyaluronan receptor was extensively detected on the cell surfaces of these osteoclasts. Therefore, an interaction between osteoclasts and hyaluronan in the cartilage was suggested at this site. Invading endotheliun also directly surrounded degraded uncalcified cartilage matrices and small deposits of cell debris. In addition, hypertrophic chondrocytes that had attached to the invading osteoclasts often enclosed the snall calcified cartilage matrices. These findings suggest unknown unique functions of endothelium, osteoclasts, and hypertrophic chondrocytes at this site.On the other hand using this grant, we executed immunohistochemical study of developmental muse condylar cartilage and rat dental pulp, and results were published or will nearly be published.