3 mice were brought aboard ISS and lived up there for 90 days. Along with thinning of skin, lost of bone and muscle mass (which affects humans too) the male mice testicles shrank in size and the rodents had almost zero sperm production.
The final frontier might be for the Ladies!
Sorry no source link. I can't find the article, but I read this story last night.
Thanks for posting the link I edited my post from 30 mice to 3. In retrospect 30 is a lot of mice to feed and water. Duh on my part!
Honestly I think all these tests are pointless. The facts are simple and plain as can be. Space is not hospitable to advanced animal life forms, period.
If the human race is serious about space exploration then we got to pony up the money for artificial gravity space stations and spaceships instead of trying to do this on the cheap. (in retaliative terms)
If the male astronauts are pre-selected for extra large testicles, then they should be approximately average size when they reach Mars ... and still have some viable sperm cells left. It's science.