Abstract：The aim of present research is to determine the localization of Crumbs-3(Crb3) in mouse testis and its distribution rules on spermatogenesis in seminiferous tubules and developmental process of Leydig's cells. We studied the histological structure and distribution of Crb3 at different postnatal development stages of mouse(Mus musculus) testis by common paraffin sectioning method stained with Hematoxilin and Eosin method and immunofluorescence histochemistry. The results showed that the diameter and thickness of seminiferous tubules increased，their lumens experienced a process from small to big, then narrowed before widened lastly as individual development. Spermatogenic cells in seminiferous tubules were in dynamic development changes, in which there were only some spermatogonium and Sertoli cells at 2th week of age, then all spermatogenic cells except spermatozoa could be seen at 4th week of age, a great quantity of spermatozoa appeared at 4th week of age after proliferation of spermatogenic cells. Then the density of spermatogenic cells increased as development. The shape of Sertoli cells became clear and easily to be recognized, and the volume of leydig cells and eosinophilic cytoplasm increased gradually, while nuclear-cytoplasmic ratio decreased gradually as development. Crb3 protein were mainly distributed in membrane of both spermatogenic cells and leydig's cells, and the positive reaction in leydig's cells were obviously stronger than that in spermatogenic cells.The results hint that Crb3 not only relates with the establishment and maintenance of seminiferous epithelium cells, but also probably participates in regulating the synthesis and secretion of steroid hormone in testis
