Ⅰ、Ⅱ、Ⅹ型胶原及碱性磷酸酶在鼠胚髁突软骨发生中的意义

The Distribution of Collagen Ⅰ,Ⅱ,Ⅹ and Alkaline Phosphatase in the Development of Condylar Cartilage of Fetal Mouse Mandible

目的 探讨髁突软骨发生中Ⅰ、Ⅱ、Ⅹ型胶原及碱性磷酸酶(ALP)的组织学分布特征及髁突软骨内成骨的 分子机制。方法 取14～18d鼠胚,分别行Ⅰ、Ⅱ、Ⅹ型胶原及ALP抗体免疫组织化学染色。结果 胚胎第14天, 髁突形成的位置可见间充质细胞聚集并与骨膜相连,间充质细胞及骨膜中Ⅰ型胶原及ALP阳性;第15天,肥大软 骨细胞中Ⅹ型胶原表达阳性,其周围的间充质细胞中Ⅰ、Ⅱ型胶原阳性,ALP在两种细胞中均呈阳性;第16天,软骨 膜、纤维层间充质细胞至肥大软骨细胞上层中Ⅰ型胶原表达阳性,多形细胞层下方至肥大软骨细胞下层中Ⅱ型胶 原表达阳性,Ⅹ型胶原仅表达于肥大软骨细胞,ALP在软骨膜及肥大软骨细胞中呈阳性,但在多形细胞层呈阴性或 弱阳性。结论 髁突软骨的发生机制与长骨不同,其软骨内成骨的早期Ⅰ、Ⅱ、Ⅹ型胶原均有表达,可能始发于ALP 阳性的下颌骨膜间充质细胞。

Objective The purpose of this study was to investigate the distribution of collagenⅠ,Ⅱ,Ⅹ,alkaline phosphatase(ALP) and their roles during initiation of condylar cartilage of the fetal mouse. Methods Coronary sections of mandible of mouse embryo aged from 14+{th} to 18+{th} day were studied under light microscope after stained by immunohistochemical method with antibody of typesⅠ,Ⅱ,Ⅹcollagen and ALP.Results On the 14th day of mouse embryo, it was found that mesenchymal cells condensation continuous with the periosteum. TypeⅠcollagen and ALP were positive behind the terminal of the ossifying mandibular periosteum where future condylar will form. On the 15th day, positive staining for typesⅠ,Ⅱ collagen was found in mesenchymal cells around hypertrophic cells and typeⅩcollagen was detected in hypertrophic cells. ALP was positive in both mesenchymal cells and hypertrophic cells. On the 16th day, typeⅠcollagen was observed from periosteal osteogenic cells and mesenchymal cells of the fibrous cell layer to the upper hypertrophic cell layer while TypeⅡcollagen was restricted from the lower polymorphic cell layer to the bottom of the hypertropic cell layer. TypeⅩcollagen was positive in the hypertrophic cell layer. ALP was positive in periosteal osteogenic cells and hypertrophic chondral cells, but not in the polymorphic cell layer.Conclusion Development of condylar cartilage is different from that of limb bone. TypesⅠ,Ⅱ,Ⅹcollagen are expressed in the condylar chondrocyte on the early stage of endochondral ossification. The histology evidence supports the conjecture that condylar cartilage is derived from differentiated mesenchymal cells of the preperiosteum or periosteum of the mandible where ALP is positively expressed.