The challenges and prospects of mammalian reproduction in extraterrestrial environments.

Humanity will eventually inhabit extraterrestrial environments, yet crucial questions remain regarding the feasibility of reproduction and long-term survival away from the Earth. Exposure to space radiation might induce DNA damage, potentially resulting in harmful mutations in future generations. Altered gravity on other planets or within space colonies could also interfere with embryonic and fetal development. For sustainable colonization beyond Earth, humans and essential animal species, e.g., livestock and companion animals, must be transported. To prevent inbreeding and genetic deterioration, hundreds of individuals per strain would need to be transferred between planets; however, moving live animals, particularly large species, might be impossible. To address this challenge, technological innovations are required for long-term preservation and secure transport of genetic resources. In addition, maintaining genetic diversity will depend on collecting genetic resources from as many individuals as possible, including those who are infertile or elderly. Although interplanetary migration is not yet practical, the technologies discussed herein are highly relevant to current challenges on Earth, including infertility treatment. This review summarizes our ongoing research on mammalian reproduction under space conditions.