By Susan Brinkmann, OCDS
While experimenting on mice, Chinese researchers discovered that an adult mammal can harbor primitive cells in her ovaries that can become new eggs capable of producing healthy offspring, thus raising the possibility that science may one day be able to help women continue to conceive later in life.
According to a report in The Washington Post, this discovery is outlined in a paper appearing in the online journal Nature Cell Biology. In the article, Ji Wu of Shanghai Jiao Tong University in China and colleagues describe how they removed ovaries from mice and sifted through millions of cells to identify a small number that appeared to have characteristics of female “germline” stem cells, which theoretically would be able to become eggs.
After identifying those cells, researchers coaxed them to multiply in the laboratory. They then tagged the cells with a jellyfish protein that would make them glow fluorescent green so they could be traced, and injected them into the ovaries of other mice that had been rendered mostly infertile with chemotherapy drugs.
Some of the mice were then killed so their ovaries could be examined, which revealed that at least some of the fluorescent green cells had indeed matured into eggs. Other mice that got the cells were allowed to breed naturally and produced offspring. Tests showed that many of the offspring also contained the green tag, which the researchers said demonstrated they were conceived from the transplanted egg cells. Tests found no evidence that the offspring, or the next generation, were abnormal in any way, the researchers reported.
“The results are very significant,” said Evelyn Telfer, who studies cell biology at the University of Edinburgh. “Of course there are always aspects of any work that need clarification, but this study appears pretty solid and I am sure that several groups will be poised to try and replicate this work.”
Other researchers have also claimed to have identified such cells in human ovaries. If it can be confirmed that they behave similarly to the mouse cells, the discovery could offer a host of new options for infertile women. For instance, scientists may be able to find a way to activate them to produce new eggs, several experts said.
Other researchers warn that caution is needed because the Chinese work needs to be repeated more carefully in mice and other species to validate the findings. Even then, it would remain far from clear whether there are any practical implications for women, some experts said.
“The aging process of the human egg differs fundamentally from that of the mouse egg,” said David L. Keefe, a professor of obstetrics and gynecology at the University of South Florida. “Except at Disney World, humans are not large mice.”
But the promise is definitely there.
“If you are looking to disprove that females cannot make new eggs, this paper proves it. It’s a really significant paper,” said Jonathan L. Tilly, a professor of obstetrics, gynecology and reproductive biology at Harvard Medical School who published some of the most controversial research suggesting that women remain capable of producing new eggs. “This is the smoking gun.”
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