In a study appearing in this week's Proceedings of the National Academy of Sciences, Stanford researchers show how they were able to activate dormant egg-producing cells - a development that might someday help improve fertility in women. A HealthDay News article describes the work:
According to background information in the study... human ovaries start with about 400,000 follicles each but only about 1,000 follicles are activated each month. The rest remain dormant. By the time of menopause, less than 1,000 follicles remain.
It's not clear why some of the follicles remain dormant, but previous research has shown that the PTEN and PI3K genes are involved.
For the new study, scientists at the Stanford University Medical School, as well as Japan and China, manipulated the PTEN and PI3K proteins to catapult the follicles of neonatal mice out of complacency. The follicles produced mature eggs, which were fertilized and then transplanted into surrogate mother mice. Those fertilized eggs resulted in 20 healthy pups capable of producing offspring themselves.
Using ovarian tissue from cancer patients, the researchers were also able to produce mature human eggs. If the method continues to work in humans in future studies, writer Amanda Gardner points out it could "significantly raise the odds of older or infertile women becoming pregnant."