Researchers discover new method for re-growing egg cells in mice.

The finding could have important implications for research into human fertility, researchers report.

Investigators at Massachusetts General Hospital and Harvard Medical School say the findings contradict the long-held belief that female mice generate their egg cells only once -- during fetal development -- and are born with a finite supply of eggs that declines as the mice age.

Secondary Production of Eggs Conceivable

Instead, the study suggests an unexpected source for progenitor cells that can prompt new egg cell production.

The study is "really revolutionizing how we think about female reproductive function," researcher Jonathan Tilly said in a prepared statement.

His team reported the findings in this week's issue of Cell.

May Lead to Multiple Therapies

The findings offer an important first step in research into whether these bone marrow and blood stem cells could potentially be used to restore fertility in humans.

The study results could also lead to future investigation into whether restoration of ovaries could delay the hormonal effects of menopause and provide an alternative to hormone replacement therapy.

The researchers added that they would like to study whether these stem cells could be used to create eggs in the laboratory and provide a new source of eggs for therapeutic cloning.

The American Society for Reproductive Medicine has information about infertility.