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Frozen balls could bring mammoths back to life
mongabay.com
August 15, 2006


Scientists have successfully bred mice using dead sperm extracted from frozen mice. The research raises the possibility that long-extinct species could one day be brought back to life.

Mammoth image from US National Parks Service.

The researchers, led by Atsuo Ogura of the Institute of Physical and Chemical Research Bioresource Center in Japan, successfully raised healthy offspring using a sperm extracted from mouse sex organs and entire mice frozen for periods ranging from a week to a year at -80 degrees Celsius. They also were able to produce healthy offspring from sperm retrieved from mice frozen at -20C for 15 years.

"Obviously, those frozen [sperm] were all dead in the conventional sense," wrote the researchers in the current Proceedings of the National Academy of Sciences. "Motionless sperm had no chance whatsoever of fertilising in vivo or in vitro. Nevertheless, some of these, if not all, were ... genomically intact, because they were able to produce apparently normal offspring."

Their findings may be significant for long-extinct species as well as species currently at risk of extinction.

"If [sperm] of extinct mammalian species (eg woolly mammoth) can be retrieved from animal bodies that were kept frozen for millions of years in permanent frost, live animals might be restored by injecting them into [eggs] from females of closely related species," wrote the scientists.

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