In a breakthrough that sent shock waves through fertility clinics, Jonathan Tilly, a reproductive biologist at Harvard Medical School, released a study in March that suggests doctors may be able to boost women’s supplies of eggs and help them bear children long after the normal onset of menopause. Biologists previously assumed that female mammals are born with a limited supply of eggs, which gradually declines with age. But the discovery of vast numbers of immature eggs dying in the ovaries of mice led Tilly’s team to find what they claim are hidden ovarian stem cells that can sprout new eggs to replace
vanishing ones.
If this proves true in humans, women in their forties, fifties, and sixties may be able to bear children by freezing stem cells at a young age and having them re-implanted at a later date. Cancer patients, often left infertile by chemical and radiation therapy, could put stem cells on ice before treatment, or drugs may be able to rev up old or damaged stem cells. Tilly has already found a molecule that boosts the number of eggs mice make. “I think it’ll be in the clinic quicker than you can dream of,” he says.
