An experiment that has produced human eggs from stem cells could be a boon for women desperate to have a baby, scientists claim.

New research has swept away the belief women only have a limited stock of eggs and replaces it with the theory the supply is continuously replenished from precursor cells in the ovary.

'The prevailing dogma in our field for the better part of the last 50 or 60 years was that young girls at birth were given a bank account of eggs at birth that's not renewable,' says Jonathan Tilly, director of the Vincent Center for Reproductive Biology at Massachusetts General Hospital, who led the research.

'As they become mature and become a woman, they use those eggs up (and) the ovaries will fail when they enter menopause.'

Tilly first challenged the 'bank account' doctrine eight years ago, suggesting female mammals continue producing egg-making cells into adulthood rather than from a stock acquired at birth.

His theory ran into a firestorm.

Other scientists challenged the accuracy of his experiments or dismissed their conclusions as worthless, given they were only conducted on lab mice.

But Tilly says the new work not only confirms his controversial idea, it takes it further.

In it, his team isolated egg-producing stem cells in human ovaries and then coaxed them into developing oocytes, as eggs are called.

Building on a feat by Chinese scientists, they pinpointed the oocyte stem cells by using antibodies which latched onto a protein 'handle' located on the side of these cells.

The team tagged the stem cells with a fluorescent green protein - a common trick to help figure out what happens in lab experiments.

The cells were injected into biopsied human ovarian tissue which was then grafted beneath the skin of mice.

Within 14 days, the graft had produced a budding of oocytes. Some of the eggs glowed with the fluorescent tag, proving that they came from the stem cells. But others did not, which suggested they were already present in the tissue before the injection.

Tilly said 'the hairs were standing up on my arm' when he saw time-elapse video showing the eggs maturing in a lab dish.

Further testing needs to be done but Tilly says the work could be far-reaching.

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Human eggs produced from stem cells

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