TYPE X COLLAGEN IN LIMB DEVELOPMENT

长骨构成四肢的主要支撑结构。 僵化的 组织首先在软骨原基周围发育，最后在软骨原基内发育。 胚胎长骨的成熟依赖于骨骼发育的同步性。 从软骨到骨骼的过渡。 该项目的长期目标是 了解软骨内骨形成的细胞调控。 的 过程可以方便地在骨骺生长板中进行研究， 细胞变化以线性连续体的形式发生。 软骨细胞通过 通过以高有丝分裂活性或高水平的 大分子合成 最后，细胞肥大， 由成骨细胞组成。 最近，一种短的胶原分子，称为X型， 胶原蛋白，已被证明是一种特定的产品的肥大 软骨细胞 本研究的目的将是检查结构 X型胶原在软骨内骨形成中的作用。 的 分子的时间和空间分布已经通过 免疫组织化学方法和提示X型胶原可能参与了 肥大软骨基质的更新或钙化。 的 分子在基质周转中的可能作用将是 通过首先定量X型与II型胶原蛋白的比例进行评估 矩阵。 第二，哺乳动物胶原酶降解 将比较X和II型。 第三，肥大的软骨会 分析是否存在能够降解X型胶原的酶。 该分子在组织钙化中的潜在功能将 也要检查。 一、羟基磷灰石的组织学分布 将其与免疫组化X型定位进行比较。 其次，将对膜内骨进行生物化学分析， X型胶原蛋白的存在，其已在组织中通过 间接免疫荧光

Long bones form the major supportive structures of limbs. The ossified tissue first develops around and finally within a cartilage primordium. The maturation of embryonic long bones is dependent on the synchronous transition from cartilage to bone. The long term goal of this project is to understand the cellular regulation of endochondral bone formation. The process may be conveniently studied in the epiphyseal growth plate where the cellular changes occur as a linear continuum. The chondrocytes pass through several stages typified by high mitotic activity or high levels of macromolecular synthesis. Finally, the cells hypertrophy and are replaced by osteogenic cells. Recently, a short collagen molecule, termed type X collagen, has been shown to be a specific product of the hypertrophic chondrocytes. The aims of this study will be to examine the structural function of type X collagen during the formation of endochondral bone. The temporal and spatial distribution of the molecule have been determined by immunohistochemical methods and suggest type X collagen may be involved in the turnover or calcification of the hypertrophic cartilage matrix. The possible role of the molecule in the turnover of the matrix will be assessed by first quantitating the ratio of type X to type II collagen in the matrix. Second, the rates of a mammalian collagenase degradation of types X and II will be compared. Third, hypertrophic cartilage will be analyzed for the presence of enzymes capable of degrading type X collagen. The potential function of the molecule in the calcification of tissue will also be examined. First, the histological distribution of hydroxyapatite will be compared with the location of type X by immunohistochemistry. Second, intramembranous bone will be analyzed biochemically for the presence of type X collagen which has been detected in the tissue by indirect immonufluoresence.