[Effect of fetal calf serum on the in vitro differentiation or maintenance of the seminiferous cords of the testis of the fetal rat].

The differentiation of seminiferous cords can be obtained in in vitro cultures, in a synthetic medium, of undifferentiated fetal Rat gonads. In older testes the seminiferous cords are maintained under these conditions. On the contrary, adding 15% fetal Calf serum to the medium prevents the differentiation of the seminiferous cords or provokes the disruption of the already formed cords (days 14 and 15). These actions are exerted upon the fetal Sertoli cells.