That line of thought was tested with the recent discovery of actively dividing germ cells (those that give rise to sexual reproduction) in the ovaries of both juvenile and adult mice. The presence of these germ cells could indicate reproductive capability.
Still, researchers disagreed as to whether female germline stem cells (FGSCs) do exist in mammalian ovaries after birth.
So, the Chinese team isolated active female FGSCs from adult and five-day-old mice. They say that they were able to generate new FGSC lines that proliferated even after being cultured multiple times.
These FGSCs restored fertility (by producing new oocytes) when transplanted into the ovaries of female mice that were previously rendered infertile by chemotherapy.
The females then gave birth to normal, young mice.
Even if the breakthrough could apply to humans, it likely would only apply to younger women experiencing infertility, Attia said. "Pregnancy is a heavy load on the human body. A 60-year-old might not be able to be pregnant," he noted.
In other stem cell news, researchers reporting Sunday in the journal Nature Biotechnology said that they were able to use bits of genetic material called microRNA to revert adult mouse cells back into embryonic cells.
These new embryonic cells are, like stem cells, capable of transforming into multiple different types of tissue.
Currently, retroviruses and genes are used to complete this transformation, but this carries the risk of cancer and other problems. Using microRNAs, which regulate gene expression, would be a potentially safer method, said researchers from the University of California, San Francisco.
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