Word: miceli
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Dates: during 2000-2009
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...maybe they do. According to a report by Tilly and several colleagues in last week's Nature, mice, at least, have specialized stem cells in their ovaries that make new eggs throughout the animals' lives. The scientists have found circumstantial evidence that the same might be true for humans. And that could--though it's theoretical at this point--lead to powerful new treatments for infertility and perhaps even for staving off menopause. "If it's true," says Roger Gosden, scientific director of the Jones Institute for Reproductive Medicine in Norfolk, Va., "it's as big a paradigm shift...
...biologists conducted several experiments to test it. In one, they looked for and found cells that appeared to be undergoing meiosis, the type of cell division peculiar to sperm and egg cells. They also detected the activity of a gene involved in that process. Then they dosed the mice with busulfan, a cancer drug known to kill the stem cells that produce sperm. Three weeks later, there were virtually no eggs left, suggesting that the drug had found a similar stem-cell target in the ovaries...
...existence of stem cells in mice, however, could indicate that menopause, or “mouse-opause,” as Tilly calls it, results not from the death of eggs, but from the gradual death of germ stem cells which produce these eggs...
This process is associated with aging in male mice as well. But, because every male has thousands of germ stem cells, as opposed to a female’s approximately 60, the decrease associated with aging is not sufficient to impair testicular functioning...
...existence of ovarian germ stem cells is known in flies and some fish and birds. Given his recent findings in mice, Tilly said, it would not be a stretch to believe that germ stem cells would have been an evolutionarily adaptive trait in human females as well...