Male fertility in space

The effects of simulated microgravity on mammalian reproduction were studied using tail-suspended mice, during parabolic flight in a jet plane and in a horizontal clinostat device. In the tail-suspended mouse, which is a model of the shift of body fluid in a microgravity environment, atrophy of the testis and decrease of serum testosterone level were observed. The sperm motility decreased in the muG condition produced by the parabolic flight. There were no statistically significant differences in the efficiency of achieving normal fertilization in vitro, but there was a statistically significant decrease in the number of embryos reaching the morula and blastocyst stages after 96 hours in culture under clinostat rotation. These results suggest that the process of fertilization in vitro is not sensitive to the gravitational vector. However, the possibility exists that microgravity increases the disturbance of spermatogenesis and sperm motility or the frequency of early embryonic lethality. On the possibility of reproduction in space, there are some problems such as the cosmic radiation besides gravity. It is necessary to carry out further experiments in outer space.