[State of spermatogenesis in rats exposed on the Cosmos-690 biosatellite].

A morphological examination of sex glands of 30 male rats flown aboard the biosatellite Cosmos-690 was carried out on the 1st-2nd and 26-27th postflight days. A combined exposure to the 20-day space flight and prolonged gamma-irradliation with doses of 220, 800 and 955 rad brought about a significant decrease of the weight of testes, postradiation death of spermatogonia and essential structural changes in the spermatogenic epithelium whose level depended on the radiation dose and the postirradiation time. A comparison of weights and histologies of testes from the flight and synchronous rats did not reveal a modifying effect of weightlessness since no statistically significant differences in the testicular weight, quantitative assay of the occurrence of individual elements of the spermatogenic epithelium and time of manifestation of reparative processes were observed.