Localization of type V collagen with monoclonal antibodies in developing dental and peridental tissues of the rat and hamster.

The distribution of collagen type V in developing dental and peridental tissues was investigated with the indirect immunofluorescence technique using unfixed, frozen sections of jaws from 1-2 day old neonatal rats and hamsters. Immunostaining for type V collagens was found both intracellularly and extracellularly in dental tissues of mesenchymal origin. In non-dental tissues, weak immunostaining was observed in the mesenchymally derived stroma surrounding the developing molar tooth germs but was more pronounced in larger cells, probably young osteoblasts in close vicinity to alveolar bone, and in some cells within developing salivary glands. Decalcification revealed a strong immunostaining in the extracellular bone matrices. In the dental tissues, the mesenchymally derived cells of the papilla exhibited an intracellular staining for type V collagen. In odontoblasts, increased immunostaining over that of other pulpal cells was observed just prior to or coinciding with the onset of predentin secretion and reactivity remained high in fully differentiated odontoblasts. A weak staining was observed in predentin but only after the onset of mineralization. As was the case for bone, after demineralization the dentin matrix stained intensely for type V collagen. The results demonstrate that type V collagen is actively synthesized by mesenchymal cells of developing hard tissues and that this type of collagen is an intrinsic component of hard connective tissue matrices. The data suggest that in developing tooth germs type V collagen is not involved in the differentiation process of either odontoblasts or ameloblasts.