| Co-Investigator(Kenkyū-buntansha) |
AKAI Junji Niigata University, Department of Geology, Professor, 理学部, 教授 (30101059)
ISHIYAMA Mikio The Nippon Dental University, Department of Histology, Lecturer, 新潟歯学部, 講師 (70120607)
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| Research Abstract |
The aim of this study was to elucidate the fine structure and the histochemical features of the biomineralization in enameloid and the dental epithelial cells which were deeply involved in the mineralization of enameloid during the late steges of odontogenesis in actinopterygians, bony fish, and to compare them with that in other vertebrates. The tooth germs in Oreochromis, Tilapia and Halichoeres, teleost, Lepisosteus (gar-pike), Holostean and Polypterus, Chodrostean were investigated by means of transmission electron microscopy and enzyme cytochemistry. The major points of results are as follows : 1) The dental epithelial cells are actively involved in the removal of the degenerated enameloid matrix as well as the material transport to the enameloid. The functions of the dental epithelial cells in the late steges of enameloid formation is essentially important to produce well-mineralized enameloid. 2) The constitution of the enamel organs is different among actinopterygians. Stratum intermedium cells which show strong Ca-ATPase are present in the enamel organ of Lepososteus. In Polypterus, stellate reticulum is always found, but no stratum intermedium. 3) The enameloid in extant fish is not an ancestral hard tissue of mammalian enamel, but rather an analogue.
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