Chinese stem cell researchers have overturned one of the bedrock doctrines of mammalian biology*–that every female mammal (including homo sapiens) is born with all the eggs she's ever going to have and that one day she'll run out them. Running out is called menopause for female members of homo sapiens. As the Washington Post reported yesterday:
In a provocative set of experiments involving mice, Chinese researchers have shown for the first time that an adult mammal can harbor primitive cells in her ovaries that can become new eggs and produce healthy offspring, they reported yesterday.
While much more research is needed to confirm and explore the findings, the work raises the tantalizing possibility that it could someday lead to new ways to fight a woman's biological clock, perhaps by stockpiling her egg-producing cells or by stimulating them to make eggs again.
Essentially the researchers searched through the ovaries of old mice for what looked like stem cells; tagged them with a gene for green fluorescence so they could be tracked; implanted them into younger female mice where they did indeed become fresh eggs. The researchers even produced baby mice using these eggs. If this technology can be made to work safely in women, it would give them the same reproductive life spans as most men have.
*Biological "doctrines" get overturned all the time. Remember way back to 1997 when cloning a mammal was supposedly impossible?