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A Key for Opening Stunted Egg Cells to Fertilization
For years, reproductive biologists were stymied by a mystery of egg cell development: What are the signals that tell immature egg cells — “primordial follicles” — to develop into mature eggs that can be fertilized?
The question is important for fertility specialists. Women entering menopause do not produce mature eggs, or produce them only occasionally, but still have primordial follicles. So do women whose ovaries fail much earlier in life. If there were a way to stimulate immature eggs to develop, it should be possible for those women to become pregnant.
And women who have cancer treatments that shut down their ovaries might want to save some immature eggs in order to have a baby later.
Now, Aaron J. W. Hsueh and Jing Li of Stanford University and their colleagues in Japan and China report that they have solved the egg maturation puzzle.
In a paper published online in the Proceedings of the National Academy of Sciences, they describe a simple way to signal immature mouse eggs to develop. They fertilized the mature eggs, got newborn mice, reared them and showed they were fertile. They also used their method to get human eggs to mature but did not fertilize them. Dr. Kazuhiro Kawamura in Japan, though, plans to take the next step with patients whose ovaries failed early in life — maturing their primordial follicles, then fertilizing the eggs, Dr. Hsueh says.