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Women May Have Infinite Number of Eggs

Women May Have Infinite Number of Eggs

Posted - Mar. 26, 2004 at 3:34 p.m.



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Dr. Kim Mulvihill Reporting For years medical schools have taught that women are born with a finite number of eggs. But new research suggests that might not be the case at all. New evidence challenges one of the most basic concepts of reproductive medicine.

This research was done on mice, but if the findings hold up in humans, it could lead to treatments to postpone menopause or to even restore fertility. The recent discovery at Massachusetts General Hospital may very well turn the world of women's fertility upside down.

Dr. Jonathan Tilly, Massachusetts General: “We’re still in a state of disbelief because this overrides or overturns one of the most basic doctrines of our field.”

For years researchers have been closely studying mouse ovaries. They discovered stem cells in the ovaries that appear to generate new eggs well into adulthood. And further work revealed a specific gene is involved in creating these new eggs.

If similar cells and genes are found in humans, it flies in the face of the old doctrine that a woman is born with a finite number of eggs in her ovaries, the supply simply runs out in middle age, and the woman then goes through menopause. The new theory suggests there is a constant turnover of eggs, which in turn might mean a turnover in the literature.

A fetus carries about seven million eggs. That kind of egg production starts to drop off precipitously. By the time you hit puberty, you have about 400,000 eggs and the body is constantly weeding out bad ones. That's the beauty of nature. But according to these findings, it may also be generating new eggs as well.

If these findings hold up in humans, what could this mean to women? This would mean different things for different women depending on their age.

If they are young women whose ovaries have stopped working or are about to undergo chemotherapy, you may be able to harvest these stem cells and conceive a child later. Or do the same if you're planning to have children much later in life.

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