We’ve always been told that men can sire babies for as along as they live, but women are born with all the eggs they’re ever going to have. Textbooks have taught this for over half a century.
Well, this week, scientists revealed that adult women have ovarian stem cells that are capable of becoming eggs.
This changes everything. The findings offer hope for women who have limited reproductive capacity including: cancer patients who have undergone sterilizing chemotherapy, women who have gone through premature menopause, or those experiencing normal aging.
"These cells, when maintained outside of the body, are more than happy to make cells on their own and if we can guide that process I think it opens up the chance that sometime in the future we might get to the point of having an unlimited source of human eggs,” says study researcher Jonathan Tilly from Massachusetts General Hospital.
His previous studies with mice have shown that females are able to generate new egg cells (or oocytes) in adulthood, but there’s a lack of evidence that such stem cells exist in humans.
So Tilly and colleagues went looking for unequivocal proof for a human population of stem cells in adult tissue. Using a technique called called fluorescence-activated cell sorting with tissue from 6 women ages 22 to 33:
- They showed that rare ‘oogonial stem cells’ (OSCs) do exist in human women of reproductive age, and that those stem cells formed oocytes in the lab.
- They also show that, in mice, oocytes derived from those stem cells can give rise to embryos after in vitro fertilization (IVF). (Ethically and legally, they couldn’t perform this kind of test in humans.)
“There’s no confirmation that we have baby-making eggs yet, but every other indication is that these cells are the real deal – bona fide oocyte precursor cells,” Tilly says.
There’s also no evidence that the OSCs form new eggs naturally in the body, but if they could be coaxed in a dish to make eggs that could successfully be used IVF, it would change the face of assisted reproduction.
Additionally, growing eggs from OSCs in the lab could help screen for hormones or drugs that might reinvigorate these cells to keep producing eggs in the body and slow down women’s biological clocks.
Image: oocyte via Wikimedia