RESUMO
Objective :The study discussed the relationship between the cell differentiation and its func-tion differentiation of enamel organ durrng the development of enamel ,explained the meaning of shape andfunction of SA and RA in the mature enameloblasts. Methods:The rats were fixed with pouring hearts ,em-bed with Epon and GMA resin,made semi-thin slice ,stained with toluidine blue and histochemistry, thenwe observed the changes of histomorphology and the law of distribution of enamel. Results:The develop-memt of tooth germ of rat incisor could be divided into proliferation stage, difference stage and maturestage. Enameloblasts expressed special periodic changes in mature stage :SA legion and RA legion present-ed altermately. Histochemical study indicated that most of amelogenin stayed in enamel matrix and othersdiffused to dentin, dental tube and odontoblast layer. Conclusion: (1) The proliferation stage, differencestage and mature stage of tooth of development of enamel organ in rat were similar to the bud stage ,capstage and bell stage of human being. There was a relationship between the RA legion in mature enam-eloblast and mineral substance pouring into them. RA legion was presented because water and protein lost.)That amelogenin spread into dentin could promote the odontoblast differentiation and induce dentin calci-fication.