Germ cell survival, differentiation, and epididymal transit kinetics in mouse testis subjected to high in vivo levels of testosterone enanthate.

Androgenic steroids induce oligospermia at high doses, but few studies have assessed which cell types and spermatogenic processes are affected. Testis cell numbers and rate of differentiation were quantitatively evaluated in testosterone enanthate-treated male mice by use of histological and cell separation techniques. Reduction in the number of testicular germ cells in treated animals accounted for 40% of the total reduction of spermatozoa. Testis cells differentiated at a similar rate in treated and control animals. Spermatozoa moved to the cauda epididymidis a day earlier in testosterone-treated animals, and were lost from the cauda after only two days, rather than after the normal seven days. These results suggest that over half of the 98% reduction in sperm number in testosterone-treated animals occurred at the stage of passage through the cauda epididymidis.