A study on biomineralization in tooth enameloid of bony fish

本研究的目的是阐明放线鸟、硬骨鱼在牙齿发育后期参与釉质矿化的釉质和牙齿上皮细胞中生物矿化的精细结构和组织化学特征，并与其他脊椎动物进行比较。用透射电子显微镜和酶细胞化学方法研究了罗非鱼、罗非鱼和盐碱鱼、硬骨鱼、梭鱼、全鱼和多翅目鱼类的牙胚。主要研究结果如下：1)牙上皮细胞积极参与了退变的釉质基质的去除和材料向釉质的转运。牙釉质形成后期牙齿上皮细胞的功能对形成矿化良好的釉质至关重要。2)不同放线鸟的釉质器官构成不同。中间层细胞在成釉细胞器内有较强的Ca-ATPase表达。在多翅目昆虫中，总是有星状网状结构，但没有中间层。3)现存鱼类的釉质不是哺乳动物牙釉质的祖先硬组织，而是类似物。

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.