Waking up ``sleeping`` eggs may boost fertility

Updated: May 18, 2010, 00:00 AM IST

London: Scientists in the US say that aging women or women who froze ovaries prior to cancer treatments may have a chance to have babies based on a novel method that can bring dormant reproductive cells into an active state.

Female mammals are born with millions of dormant eggs, but only a small fraction ever mature into cells with reproductive potential.

One factor keeping cells in this immature state is the PTEN gene, which suppresses a signalling pathway involved in cell growth.

As part of the study, Aaron Hsueh at Stanford University Medical School in California and his colleagues exposed mouse ovaries to a PTEN inhibitor and a molecule that stimulates the signalling pathway that PTEN inhibits, reports New Scientist.

Control ovaries remained untreated. The ovaries were then transplanted back into the mice, and they received a hormone to stimulate egg development.

Two weeks later, the treated ovaries contained two to six times as many mature follicles – which have the potential to release mature eggs – as the untreated ones.

Twenty healthy mouse pups were born after fertilised eggs from the treated ovaries were implanted into surrogate mothers.

Hsueh``s team has used a similar approach to stimulate fragments of human ovarian tissue. When these were implanted into mice, four times as many mature follicles were produced as in controls. But for ethical reasons, the eggs could not be fertilised.

The study has been published in the Journal Proceedings of the National Academy of Sciences.