Proliferative and steroidogenic effects of follicle-stimulating hormone on cultured chick embryo testis cells

The present study evaluated the follicle-stimulating hormone (FSH) effect on cell proliferation and steroid production by chick embryo testis. Dissociated cells from 18-d-old embryos were cultured on polycarbonate membranes in defined media. In some experiments, cells were further separated by a metrizamide gradient, and 5 cellular subpopulations were recovered and cultured. [H-3]thymidine was added to the culture media. When necessary, 17beta-estradiol, human FSH (hFSH), recombinant human FSH (rhFSH), or human chorionic gonadotropin (hCG) was added to the medium at the beginning of the culture. The total number of cells and the incorporation of [H-3]thymidine increased when hFSH or rhFSH was added. No changes were produced by the addition of hCG or 17beta-estradiol. The dose-response curve to hFSH resulted in an ED50 of 0.25 IU/mL. The stimulatory effect of hFSH on total number of cells and on [H-3]thymidine incorporation was significant at 36 h of culture and was maintained up to 60 h. Testosterone production increased with the addition of FSH or rhFSH, meanwhile estradiol production was below the limit of detection of RIA. The hFSH proliferative effect measured as [H-3]thymidine incorporation was observed only in the F3, F4, and F5 fractions of the density gradient. Present results show that hFSH and rhFSH, but not hCG or estradiol, stimulate testis cell proliferation in a time- and dose-dependent manner. The combination of [H-3]thymidine incorporation and testosterone production in fractions obtained from the metrizamide density gradients suggests that the cell fractions of the chick embryo testis show a differential response to FSH.