Basement membrane-like structures occurring on the surface of dental papilla mesenchymal cells during odontogenesis in the monkey Macaca fuscata

The aim of this study was to examine the nature of a basement membrane-like structure occurring along the surface of dental papilla cells during odontogenesis. The tooth germs of Japanese macaques (Macaca fuscata) were prepared for both ultrastructural and immunohistochemical studies. Characteristic discrete structures which resembled basement membranes were observed along the surface of the dental papilla cells, preodontoblasts, and also of the odontoblasts. Immunoperoxidase staining showed that these structures contained major basement membrane components including laminin, heparan sulfate proteoglycan, type IV collagen, as well as fibronectin. They tended to be less prominent along dental pulp fibroblasts and fully developed odontoblasts in comparison with those along the papilla cells localized close to the basement membrane of the inner enamel epithelium. Therefore, possible roles of these basement membrane-like structures would be: 1) to support the cells, 2) to momentarily secure the appropriate positions of differentiating mesenchymal cells, and 3) to regulate epithelial-mesenchymal interactions for odontoblast differentiation.