title: [The distribution of collagen I, II, X and alkaline phosphatase in the development of condylar cartilage of fetal mouse mandible].
abstract: OBJECTIVE
  The purpose of this study was to investigate the distribution of collagen I, 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 14th to 18th day were studied under light microscope after stained by immunohistochemical method with antibody of types I, II, X collagen and ALP.
  
  
  RESULTS
  On the 14th day of mouse embryo, it was found that mesenchymal cells condensation continuous with the periosteum. Type I collagen and ALP were positive behind the terminal of the ossifying mandibular periosteum where future condylar will form. On the 15th day, positive staining for types I, II collagen was found in mesenchymal cells around hypertrophic cells and type X collagen was detected in hypertrophic cells. ALP was positive in both mesenchymal cells and hypertrophic cells. On the 16th day, type I collagen was observed from periosteal osteogenic cells and mesenchymal cells of the fibrous cell layer to the upper hypertrophic cell layer while Type II collagen was restricted from the lower polymorphic cell layer to the bottom of the hypertropic cell layer. Type X collagen 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.
  
  
  CONCLUSIONS
  Development of condylar cartilage is different from that of limb bone. Types I, II, X collagen 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.
authors.affiliation: Key Laboratory of Oral Biomedical Engineering Ministry of Education, Sichuan University, Chengdu 610041, China.
authors.forename: Xiao-qing
authors.initials: XQ
authors.lastname: Li
authors.forename: Lai-kui
authors.initials: LK
authors.lastname: Liu
authors.forename: Xin-zhu
authors.initials: XZ
authors.lastname: Yi
authors.forename: Yu-juan
authors.initials: YJ
authors.lastname: Hong
authors.forename: Bi-jie
authors.initials: BJ
authors.lastname: Han
mesh_terms: D000469:Alkaline Phosphatase; D000818:Animals; D002356:Cartilage; D002454:Cell Differentiation; D019902:Chondrocytes; D003094:Collagen; D024042:Collagen Type I; D008334:Mandible; D008335:Mandibular Condyle; D051379:Mice; D010012:Osteogenesis
chemical_list: D024042:Collagen Type I; D003094:Collagen; D000469:Alkaline Phosphatase