[The state of bone tissue in monkeys in experiments in the Cosmos-1887 biosatellite].

Using invasive and noninvasive techniques, we studied bone changes in primates flown for 13 days on Cosmos-1887 and compared them with the data obtained from vivarium control animals and from the flown primates that were after flight exposed to a ground-based synchronous experiment in the biosatellite mockup. It was found that bone density in the diaphysis of the tibia decreased while its growth rate remained unchanged or diminished. Contact X-raying indicated a higher rate of endosteal resorption in the flown primates when compared with the controls. Histomorphometric measurements of iliac bioptates displayed signs of inhibited bone formation after flight. The above observations are discussed and compared with the results obtained in previous biosatellite flights and ground-based studies.