State of spermatogenesis in rats flown aboard the biosatellite Cosmos-690.

Testes of 30 rats flown aboard the biosatellite Cosmos-690 for 20.5 d and 30 rats kept in a ground-based experiment, which simulated all flight except weightlessness and accleration, were examined morphologically. On the 10th experimental day the rats were exposed for 24 h to gamma irradiation from a Cs137 source at doses of 220, 800, and 955 rad. Tests from 60 nonirradiated rats that remained in the vivarium were used as controls. On the 1st-2nd and 26-27th post-experimental days the animals showed a significant decrease in the weight of testes, post-radiation death of spermatogonia, and important structural changes in the spermatogenic epithelium, whose level depended on the dose of irradiation and the time elapsed after the exposure. No significant differences in the weight of testes, frequency of occurrence of individual components of the spermatogenic epithelium, and time of emergence of reparative processes were noted. No modifying effect of space flight factors on the development of radiation-induced changes in the spermatogenic epithelium of rats was found.