Proliferative and steroidogenic effects of follicle-stimulating hormone during chick embryo gonadal development

The aim of this study was to evaluate the in vitro effect of human follicle -stimulating hormone (hFSH) on cellular proliferation and steroid hormone s ecretion in the left ovary,:the: right ovary, and the testis of the chick e mbryo. Gonads from 8- to 18-day-old chick embryo were cultured in a defined medium during 60 h under basal and hFSH-stimulated conditions (0.5 IU/ml o f culture medium). At the end of the culture, the incorporation of [H-3]thy midine and the total number of cells were measured to estimate gonadal cell proliferation. The secretion of 17 beta-estradiol and testosterone in the culture medium Was radioimmunologically assayed in order to evaluate the st eroidogenic function of the cultured gonadal cells. The response to hFSH st imulation was observed in the left ovary, the right ovary, and the testis f rom the 8-day-old chick embryo. In the left ovary, cellular proliferation w as not augmented by hFSH in the 8-, 10-, and 13-day-old chick embryo; meanw hile, the proliferative stimulus of hFSH was observed in the 15- and 18-day -old embryos. In the same ovary, 17 beta-estradiol and testosterone secreti on were stimulated after hFSH treatment at all evaluated stages (8-18 days of chick embryo development). In the right ovary, an increment in prolifera tion and steroidogenesis was induced by hFSH in the 8-, 10-, and 13-day-old chick embryo. Afterward, the right gonad did not respond to hFSH. Testis c ells displayed hFSH response as an increment in cell proliferation at all e mbryonic ages (8-18 days of chick embryo development). There was a transien t lack of response to hFSH in testosterone secretion at 10 and 13 days of d evelopment. The in vitro effect of hFSH on cell proliferation and steroid h ormone secretion changed in the ovary and the testis according to the age o f the embryo. These changes could be attributed to the growth of the left o vary and the testis and the regression of the right ovary. Probably, paracr ine factors modulated the gonadotropin effect on the target cells during em bryonic development of chick embryo gonads. (C) 1999 Academic Press.