Abstract：This study was performed to explain effect of Sertoli cells on spermatogenesis. Testes of porcine from 7 d-old, 21 d-old, 35 d-old were used, and the methods including cell count, immunohistochemistry, flow cytometry and western blot were used. The results were as follows: (1)from 7 d to 21 d , the boundary between Sertoli cell and other cells in seminiferous tubules was more significant. From 7 d to 35 d, the number of Sertoli cells and Leydig cells and of per gram of testis increased(P<0.05), and the number of both cells were the most at 21 d(P<0.05). After that period, the number of both cells of per gram of testis began to decrease(P<0.05). However, the number of germ cells of per gram of testis continued to increase(P<0.05), but round spermatids could not be found in the seminiferous tubule. (2) form 7 d to 35 d, both of Sertoli cells and Leydig cells could express GATA-4, and the integrated optical density(IOD) of GATA-4 of Sertoli cells was the most at 21 d(P<0.05), but that of Leydig cells between at 21 d and 35 d had no difference(P>0.05). (3) form 7 d to 35 d, total testical cells had proliferation capacities, while PI and SPF in testes were the most at 21 d(P<0.05). During the periods, three types of cells(Sertoli cells, Leydig cells and germ cells) could express PCNA, and the IODs of PCNA of three cells were the most at 21 d(P<0.05). the expression of PCNA(Proliferating Cell Nuclear Antigen) in the testes was the most at 21 d(P<0.05). (4) form 7 d to 35 d , Connexin 43(Cx43) was mainly expressed in cytoplasm of Sertoli cells, and the IODs of Cx43 of Sertoli cells and Leydig cells were the most at 21 d(P<0.05). The results infer that it is an important proliferation peroid form 7 d to 35 d, but these immature sertoli cells could not support spermatogenesis.
