Hormonal control of seminiferous tubule contractions. A hypothesis of sperm transport from the testicle.

In vivo and in vitro experiments were conducted to evaluate the effects of testosterone (T) dihydrotestosterone (DHT) and estradiol (E1) on seminiferous tubule contractions in the rat. The percentage of seminiferous tubules exhibiting contractions was reduced by both 10 and 30 mg implants of E1 and in vitro concentrations of 10 (-8) or 10(-9) M E1. However the magnitude of the contractions was not altered. Tubular contractions were maintained at normal or above normal values by higher doses of T and DHT both in vivo and in vitro whereas both the percentage and magnitude of tubular contractions were reduced by lower doses of the androgens. The results indicate that steroids can alter rat seminiferous tubule contractions and thus may regulate sperm transport from the testicle.