Comparative and Histogenetics study on origin, development and evolution of enamel structure on human tooth

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The origin and the development of the enamel structure were examined, and the meaning was discussed.The ameloblasts of crocodilian enamel forms groups (Grouping) admitted to the crystal unit in enamel. The boundary of each crystal unit is not corresponding to boundaries of the ameloblasts groups, and also differenced to the boundary of Hunter-Schreger band. It is clear that the boundary relates to the enamel tuft and lamella of mammalian enamelThe enamel prism in primitive mammals shows winding run with disappearance of enamel tubules along with the development. It is suggested the movement of the ameloblast is influenced (or controled) by the odontoblastic process. The Hunter-Schreger band appears as sets of islanded of enamel prisms groups in primitive mammals as compare from fossil to resent mammals. The island prism groups expand horizontal direction where the tooth crown is surrounded. The expanding patterns were variable in each mammalian species, but horizontal type of Hunter-Sc … More hreger band is basic pattern in many mammals. This was named 'Grouping' of the enamel prism. The enamel prism runs not only in one zones of Hunter-Schreger band but also changes the course one to the other zones. Other enamel prism pattern runs only the boundary of zones. This was named 'Dancing' of the enamel prism.In an examination of tooth germs of dog etc. with the immunocytochemical method, the localization of the actin showed the grouping form in the outer enamel epithelium, stellate reticulum, stratum intermedium, and ameloblasts as Hunter-Schreger bands.The keratins showed similar localization of 'Grouping' of the enamel prism. It is clear that that grouping and moving of enamel organ forms the Hunter-Schreger bands.The actin localization in Tome's process of amelobast showed original movement besides grouping. It is showed that the dancing of Tome's process formed the patterns of enamel prism arrangement, so called 'Dancing'Further studies to clarify the factor to control these movements will have done in the future. Less