An amazing story today in Nature. The lead:
Scientists have found hints that mammals' ovaries produce new eggs throughout life, a finding that might herald new treatments for infertility and the menopause.Here is the NY Times coverage, with this great lead:The discovery challenges a decades-old dogma that women and other mammals are born with a limited supply of immature eggs. These were thought to be expended by decay, death or ovulation until, at menopause, the supply was exhausted.
Now US researchers have unearthed evidence in a mouse's ovary of stem cells that churn out fresh eggs during its reproductive years. This suggests ovaries have more in common with the male's testicular sperm factory than had been thought.
"We are still reeling," says Jonathan Tilly of Harvard Medical School, Boston, who led the Nature study.
Challenging the bedrock verity of mammalian biology that a female's eggs, like private reserve wines, are made one time only, in limited numbers, and are apt to turn to vinegar if left on the shelf too long, researchers have found startling evidence that the ovaries may instead be replenished with new eggs throughout a female's reproductive career.And this from the Washington Post:
For more than half a century, textbooks have taught that female mammals -- be they mice, cows or women -- are born with all the eggs they will ever have.Posted by Marcia Oddi at March 11, 2004 08:19 AMThe result is one of the great sexual disparities: Males, which make fresh sperm daily, can sire children at virtually any age, whereas females gradually deplete their limited supply of eggs to the ticking of the biological clock.
Now Harvard researchers have come to the radical conclusion that female mice produce a constant stream of new egg cells as adults -- challenging a central dogma of reproductive biology and raising the heretical possibility that women, too, clandestinely produce fresh eggs for at least the first half of life.