Stimulation by follicle-stimulating hormone of DNA synthesis and of mitosis in cultured Sertoli cells prepared from testes of immature rats

Abstract

Follicle-stimulating hormone (FSH) or dibutyryl 3',5'-cyclic AMP (dbcAMP) increases the incorporation of [ 3H] thymidine into DNA of cultured Sertoli cells prepared from testes of rats from 4 up to 40 days of age. The amounts of DNA synthesis are shown to be inversely related to the density of the cultured Sertoli cells, and are maximal at periods 4–6 days after plating. At a given cell density the extent of DNA synthesis by primary cultures of unstimulatsd Sertoli cells is greatest in preparations from testes of rats 10 days of age or younger. The percentage of Sertoli cells capable of responding to FSH or dbcAMP with increased incorporation of thymidine into DNA becomes progressively smaller in preparations from testes of rats older than 20 days of age. The extent of DNA synthesis in Sertoli cells at different stages of development is well correlated with the percentage of cells observed to have labeled nuclei, as measured by radioautographic examination, and with the mitotic index. The frequency of mitosis of Sertoli cells, cultured in the presence of FSH, is greatest in cells prepared from testes of younger rats. Evidence is presented that the percentage of Sertoli cells which retain the capacity to undergo mitosis is reduced to nearly zero in preparations from rats older than 40 days. It is concluded that the stimulation of DNA synthesis in cultured Sertoli cells elicited by FSH or dbcAMP is directly associated with an increased mitotic frequency.