To contradict the belief that women are born with a finite number of eggs, scientists have discovered stem cells in the ovaries of adult mice that seem to give rise to new eggs and healthy offspring.
If confirmed in humans, the above findings may revolutionize female reproduction by paving the way for women to delay child-rearing almost indefinitely.
It could also offer a new source of eggs for women who have been rendered infertile.
In the study, Ji Wu and his colleagues at Shanghai Jiao Tong University in China isolated the mouse ovarian stem cells, dubbed female germline stem cells (FGSCs).
For this, they tried to find cells producing an egg-related protein called MVH in the ovaries of adult and five-day-old female mice.
Later, they identified rapidly dividing cells and grew them in culture, where they continued to proliferate.
Finally, they injected the FGSCs into the ovaries of mice that had previously been sterilized by chemotherapy.
It was found that new eggs formed in the ovaries and the mice subsequently became pregnant and gave birth to healthy offspring.
To confirm that the offspring really did come from the implanted eggs, Wu had inserted a gene encoding a fluorescent protein into the stem cells, which some of the offspring were also found to be carrying.
"By producing live young, these cells have passed the ultimate test to prove their germline credentials. It's very, very exciting," New Scientist magazine quoted Evelyn Telfer of the University of Edinburgh, UK, as saying.
Now, independent labs will try to replicate the above results.
"Stem cell biology has been mired in the problem of replication, and a very high standard of proof is needed," said Roger Gosden of Weil Cornell Medical College in New York.
If the cells were found to exist in humans and can be extracted, it would open the doors to growing large numbers of eggs in a dish to repopulate damaged or depleted ovaries.
It would then be used to create embryos for childless couples, or embryonic stem cell research.