The overlapping effects of thyrotropin and gonadotropins on chick embryo gonads in vitro.

Pieces of 12- and 15-day-old chick embryo testes and ovaries were cultured in vitro in the presence of thyrotropin (TSH), gonadotropins (FSH + LH) and adrenocorticotropin (ACTH) for different periods. All the explants of treated gonads differentiated into typical testes or ovaries according to their genetic sex. The gonads of 12-and 15-day-old chick embryos showed a good response to both thyrotropic and gonadotropic stimulation. On the other hand, they did not respond to adrenocorticotropic stimulation. Fifteen-day-old chick embryo testes were grown in tissue culture in the presence of the said hormones. Gonadotropins and TSH enhanced the growth and migration of testicular cells as compared with the control or ACTH treated group. In addition, they maintained the germ cells on the upper surface of epithelial cells. These results have confirmed our previous results in vivo in that gonadotropins and thyrotropin hormones accelerated the development of 12- or 15-day-old chick embryo gonads.