Women 'have potentially endless supply of eggs'
WOMEN could have the opportunity to give birth with their own eggs later in life thanks to the discovery that they possess a potentially "unlimited" supply of them, scientists have discovered.
Their ovaries contain stem cells which can "spontaneously" generate into immature eggs in the laboratory, according to the American team.
The prevailing wisdom has been that women have a finite number of eggs, that gradually diminish in number and quality until the menopause.
But British experts said the findings, published in the journal Nature Medicine, "re-write the rule book" on this point and amounted to "a potentially landmark piece of research".
The academics, led by Dr Jonathan Tilly of Massachusetts General Hospital, managed to identify and extract human stem cells that can go on to become immature eggs, because all carry a unique protein called DDX4.
These "spontaneously generated" into immature eggs, called oocytes, in the laboratory.
Using live ovarian tissue grafted into mice, these oocytes cells were made to mature into egg cells.
The researchers also took the science on - but using mice stem cells for the whole process - to show that this type of cell could then be fertilised with sperm to produce embryos.
Dr Tilly said the study "opens the door for development of unprecedented technologies to overcome infertility in women and perhaps even delay the timing of ovarian failure".
He continued: "I think it opens up the chance that sometime in the future we might get to the point of having an unlimited source of human eggs."
Dr Allan Pacey, an expert in male fertility at Sheffield University, told the BBC: "Not only does this re-write the rule book, it opens up a number of exciting possibilities for preserving the fertility of women undergoing treatment for cancer, or just maybe for women who are suffering infertility by extracting these cells and making her new eggs in the lab."
Stuart Lavery, a consultant gynaecologist and IVF specialist at Hammersmith Hospital in London, described the report as "extremely significant" and "a potentially landmark piece of research".
He said: "If this research is confirmed it may overturn one of the great asymmetries of reproductive biology - that a woman's reproductive pool of gametes may be renewable, just like a man's."
However, they cautioned that there was still a long way to go before showing the process was viable in humans.