Transmission and scanning electron microscopy of epididymis in male mice receiving estrogen during gestation.

In estrogen-induced cryptorchidism in mice, differentiation of the epididymis is arrested. Transformation of the Wolffian duct into the epididymis, which is androgen dependent, is incomplete. Simultaneous administration of estrogen and HCG prevents cryptorchidism, and the appearance of the epididymis in the transmission and the scanning electron microscope is similar to the appearance of the epididymis of control animals. According to our studies the epididymis differentiation is a prime mover in a process which leads to the descensus of the testis.