[Effect of space flight on the course of radiation lesions in the lymphoid organs of rats].

The spleen, thymus and inguinal lymph nodes of rats exposed to a prolonged (24 hours) irradiation at a dose of 800 rad on the 10th day of the 20-day space flight aboard the biosatellite Cosmos-690 were examined histologically and cytologically. The lymph organs showed the changes typical of radiation-induced lesions. They did not display an aggravating or modifying effect of space flight factors on the development of radiation-induced lesions in lymph organs. It is emphasized that radiation-induced lesions at the above irradiation dose may mask weightlessness-induced effects in lymph organs.