Basic parameters of spermatogenesis in 6 almost healthy males aged from 26 to 41 volunteered in 500 day isolation experiment were studied. During 500 days they were in conditions imitating a manned flight. Male sexual function was evaluated due to BSF 1 criteria. Initial results were normal due to WHO recommendations. 500 days after isolation, detachment from common working rhythm and sexual abstinence in ejaculate analysis multidirectional influence of these factors were discovered. Increase of average ejaculate volume from 2.3 ml to 3.4 ml with synchronous increase of sperm concentration from 84 mln/ml to 99 mln/ml, however these increases were statistically unreliable. Sperm cell activity didn’t change significantly too: general mobility initially was 53%, after the experiment 48%, active mobility 24% and 22%, moderate mobility – 28% and 26% respectively. Most significant changes were found in of alive and normal forms of sperm cells. Quantity of alive cells reliably decreased from 73% to 62%. Quantity of normal cells decreased from 51% to 38%. Quantity of lecithin grains also decreased from 12 to 7 in sight.

Similar data was obtained in a previous 105 days isolation experiment with 6 men. Comparison of two groups shows the same tendency in ejaculate changes.

Results can have a practical value in evaluation of isolated groups, including spaceship crews.