HIGH-RESOLUTION IMMUNOCYTOCHEMISTRY OF DENTAL BASEMENT MEMBRANE

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1. A characteristic layr containing numerous fibrils is associated with the basement membrane (BM) of the inner epithelium during the early stages of odontogenesis. Tooth germs of monkeys were studied and each fibril in the layr (lamina fibroreticularis) was found to be a tubular structure, 8-9 nm in width, resembling a "basotubule", the tubular structure previously observed in various BMs. The space between the fibrils was filled with a network formed by irregular anastomosing strands with an average thickness of 4 nm ; these strands resembled the "cords" forming the network in the lamina densa of BMs.2. Immunoreaction for type IV collagen, laminin, and heparan sulfate proteoglycan were observed both in the lamina densa and lamina fibroreticularis. Fuzzy substances occurring very close to the lamina fibroreticularis manifested moderate immunoreactivity. The dental papilla cells located close to the BM demonstrated immunoreactive material mainly on the plasma membranes facing the BM.Re … More action products were also observed in large concavities formed in some area of the cell surfaces ; and small, immunopositive vesicles occurred close to the plasma membrane. Immunoreaction products could be found in the rough endoplasmic reticulum of some cells. These findings suggest that dental papilla cells may produce the BM components that are incorporated into the dental papilla BM - particularly into the lamina fibroreticularis - during tooth development.3. Labelling for fibronectin was mostly associated with the lamina fibroreticularis. Enamel proteins were also immunodetected in association with the lamina fibroreticularis and gradually accumulated as patches within mantle dentin and at its interface with ameloblasts. Patches of granular material, immunoreactive for fibronectin and/or enamel proteins were found along the odontoblastic processes and cell bodies. These data suggest that enamel proteins, by themselves or synergistically with other proteins, may play a part in the differentiation and/or formative events taking place at the ameloblast-odontoblast interface during the early stages of tooth development. Less