Expression of basement membrane components in the dental papilla mesenchyme of monkey tooth germs - An immunohistochemical study

The present work, which employs indirect immunoperoxidase methods, demonstrates electron microscopic localization of three major basement membrane (BM) components - type IV collagen, laminin, and heparan sulfate proteoglycan - at the early stages of odontogenesis in tooth germs of the Japanese macaque (Macaca fuscata). Intense immunostaining for each examined component occurred at the interface between the inner enamel epithelium and the dental papilla mesenchyme. At higher magnification, immunoreaction products were observed both in the lamina densa and lamina fibroreticularis. Fuzzy substances occurring very close to the lamina fibroreticularis manifested moderate immunoreactivity. In addition, immunostaining took place in the dental papilla mesenchyme. The dental papilla cells located close to the BM demonstrated immunoreactive material mainly on plasma membranes facing the BM. Reaction products were also observed in large concavities formed in some areas of the cell surfaces; and small, immunopositive vesicles occurred close to the plasma membrane. Immunoreaction products could be found in the cisternae of the rough endoplasmic reticulum of some mesenchymal cells. These findings suggest that dental papilla mesenchymal cells may produce the three major BM components and those of the components that are incorporated into the dental BM - particularly into the lamina fibroreticularis - during tooth development.