Waking dormant eggs may boost fertility

A US study on mice has given hope to women with reduced fertility, including those receiving treatment for cancer. If transferable to humans, it seems activating dormant eggs could increase the chances of conception.

Female mammals are born with millions of eggs, but only a small fraction of these mature into eggs capable of fertilisation, with the rest remaining dormant. Scientists successfully activated dormant eggs by treating newborn mouse ovaries with a chemical that stimulates cell growth. The ovaries were than transplanted into surrogate mice, which, after two weeks contained two to six times more mature follicles (structures capable of releasing mature eggs) than the ovaries of untreated control mice. Furthermore, when eggs from the treated ovaries were fertilised in vitro and implanted into surrogate mothers, 20 healthy pups were produced.

The researchers also stimulated fragments of human ovarian tissue to test if the technique was feasible in humans. After implanting the treated tissue into surrogate mice, four times more mature follicles were produced than in untreated control mice. For ethical reasons, these eggs could not be fertilised and this, along with the biological differences between mice and humans, makes it difficult to assess how successful this technique will be in humans.

The study's first author Dr Jing Li said: 'it's long-term work to see if this method works as well in humans, although we have already seen it can activate human dormant follicles in our study'.

'We hope that ageing women, women who have frozen ovarian tissues prior to undergoing cancer treatments, or women with premature ovarian failure could benefit from our research', she added.

The study was published online in the Proceedings of the National Academy of Sciences.