So far they’ve succeeded with mice some frozen as long as 15 years and lead researcher Dr. Atsuo Ogura says he would like to try experiments in larger animals.
“In this study, the rates of success with sperm from 15 year-frozen bodies were much higher than we expected. So the likelihood of mammoths revival would be higher than we expected before,” Ogura said in an interview via e-mail.
While frozen sperm is commonly used by sperm banks, the team led by Ogura, at Riken Bioresource Center in Ibaraki, Japan, worked with sperm from whole frozen mice and from frozen mouse organs.
“If spermatozoa of extinct mammalian species can be retrieved from animal bodies that were kept frozen for millions of years in permafrost, live animals might be restored by injecting them into (eggs) from females of closely related species,” the researchers said in a paper appearing in Tuesday’s issue of Proceedings of the National Academy of Sciences.