Inhibition of development of both androgen-dependent and androgen-independent pigment cells in scrotal skin dermis of the rat by antiandrogen treatment during fetal growth.

Testosterone controls the melanogenic activity of epidermal melanocytes, but not that of brown dermal pigment cells, in scrotal skin of the adult rat. The effect of prenatal treatment with the antiandrogen flutamide on the development of scrotal skin pigmentation and the male reproductive system was examined. Treatment with flutamide on days 14-20 of gestation resulted in hypospadias, the absence or only rudimentary growth of prostate and seminal vesicles, and the presence of a vagina in male offspring. The scrotal coloration of these animals was lighter than controls, an effect due to the complete absence of dermal pigment cells. There was no effect of prenatal treatment with flutamide on melanin content, morphology, and relative number of epidermal melanocytes. Thus, the administration of antiandrogen during the fetal period of androgen-induced differentiation of secondary genital organs of the male rat prevents development of the androgen-independent dermal pigment cells. It would appear, therefore, that there is a transitory period during development when the dermal pigment cells or other elements in the scrotal dermal environment which regulate their function are under androgen control.