Abstract
Newborn BALB/c and BALB/cfC3H male mice were given 5 daily injections of 17.beta.-estradiol and progesterone, alone and in combination, beginning within 36 h after birth. Mice were killed and autopsied between 19-27 mo. of age. Mice treated neonatally with 17.beta.-estradiol showed a complete inhibition of spermatogenesis in 71% of the BALB/c substrain (compared with 30% in the controls) and in 62% of the BALB/cfC3H substrain (compared with 0% in the controls), with 8 and 10 animals, respectively, having at least 1 testis completely atrophied. Estradiol alone resulted in epididymal cysts and some metaplastic changes in the secondary sex accessories in both substrains. Estradiol/progesterone combinations resulted in similar abnormalities in the male genital tract of both substrains; progesterone alone was not as effective.