Mouse gonadal differentiation in vitro in the presence of fetal calf serum

Other workers have shown that fetal calf serum (F.C.S.) inhibits the differentiation of the rat testis, and disrupts established testicular cords, in vitro. To investigate the possibility of a serum effect in the mouse, indifferent urogenital complexes and differentiated gonads were removed from sexed fetuses and cultured for 7 days in medium with or without the addition of fetal calf serum. Cultures were assessed by light and electron microscopy. Testicular and ovarian differentiation occurred in the presence of fetal calf serum. Serum did not prevent basal lamina development in testicular cords of explants cultured to the equivalent of day-17 control testes.