Comparative study on the formation of biominerals in enamel and enameloid

覆盖在硬骨鱼类牙齿表面的类牙釉质具有非常高的矿化程度，似乎具有与哺乳动物牙釉质相似的功能。采用透射电镜和酶细胞化学方法观察了鳍鱼牙釉质形成阶段构成牙釉质器官的牙上皮细胞。在矿化和成熟阶段，牙内上皮（IDE）细胞的远端质膜明显卷曲，细胞质中存在许多线粒体和酸性磷酸酶阳性溶酶体。非特异性碱性磷酸酶、钙依赖性腺苷三磷酸酶和钾依赖性对硝基苯磷酸酶的活性通常在IDE细胞矿化和成熟阶段的质膜上检测到。这些结果表明，牙釉质上皮细胞在牙釉质矿化和成熟阶段主要参与了牙釉质基质的变性和迁移，并参与了物质的运输，这些功能对牙釉质大晶体的形成起着重要的作用。项圈珐琅质，以及帽类珐琅质，是在勒皮索斯和多角龙的下颌牙齿中发现的。这意味着我们可以在牙齿发育过程中观察到牙帽类牙釉质形成后的成釉发育。本研究采用猪淀粉原蛋白c端、中央和n端特异性抗体的光镜和电镜免疫组化方法检测颈釉质基质。釉质基质对c端和中心区域特异性抗体表现出强烈的免疫反应。结果表明，硬骨鱼类的釉质基质中含有一个与猪淀粉原蛋白的c端和中心区域非常相似的结构域。领釉中晶体的大小与类釉中晶体的大小相比没有那么大。由于牙釉质上皮细胞的吸收功能较弱，导致了牙釉质与类牙釉质之间的差异。少

The enameloid covering the surface of the teeth in bony fishes exhibits a very high degree of mineralization, and seems to have functions similar to the enamel in mammals. The dental epithelial cells constituting enamel organs during the enameloid formation stages in rayfinned fishes were observed by transmission electron microscopy and enzyme cytochemistry, which detects hydrolytic enzyme activities. During the mineralization and maturation stages, infoldings of the distal plasma membrane in the inner dental epithelial (IDE) cells were marked, and many mitochondria and acid phosphatase positive lysosomes were present in the cytoplasm. The activities of non-specific alkaline phosphatase, calcium-dependent adenosine triphosphatase and potassium-dependent p-nitrophenylphosphatase were usually detected at the plasma membrane of the IDE cells during the mineralization and maturation stages. These results suggest that the dental epithelial cells are mainly involved in the degeneration and r … More emoval of enameloid matrix and in material transportation during the enameloid mineralization and maturation stages, and that these functions are very important to make large crystals in enameloid.Collar enamel, as well as cap enameloid, is found in the jaw teeth of Lepi sosteus and Polypterus. This means that we can observe amelogenesis following cap enameloid formation during tooth development. In this study, light and electron microscopic immunohistochemistry using antibodies specific to the C-terminal, central and N-terminal regions, respectively, of porcine amelogenin was performed to examine the collar enamel matrices. The enamel matrices showed intense immunoreactions to the C-terminal and central region-specific antibodies. The data suggest that the enamel matrix in bony fishes contains a domain that closely resembles the C-terminal and central regions of porcine amelogenin. The size of crystals in collar enamel was not so large in comparison with that in enameloid. Less absorptive function of the dental epithelial cells on the collar enamel might cause the difference between enamel and enameloid. Less