A new study that challenges the theory that female mammals are born with a finite number of oocytes (eggs) has found that despite their age, female mice have a renewable supply of eggs in their ovaries.
The discovery was made by Professor Jock Findlay from Prince Henry's Institute and Associate Professor Jeff Kerr from Monash's Department of Anatomy and Cell Biology, who say that the findings could have broad implications for women's fertility treatments.
Professor Findlay and Dr Kerr's research gives support to a theory made two years ago by international researchers who speculated that mice could continue to produce eggs throughout puberty and adulthood. At the time the scientists could not produce evidence to confirm their idea.
In the mammalian ovary, reproductive cells called oocytes (eggs) develop within ovarian follicles. In humans, the eggs are believed to die off from late in foetal life, after birth and into adult life.
The researchers found that the total number of eggs in young and normal healthy adult female mice does not decline over time, and that overall egg number is maintained for longer than previously thought.
"The mechanism behind renewable oocytes is still unknown. Although other scientists have suggested that the new eggs come from stem cells in the bone marrow or the ovary, we really don't know and further experimentation is needed to find out," Prof Findlay said.
Dr Kerr said the phenomenon of egg regeneration in mice did not necessarily mean the same happened in humans.
"But the mechanism could provide direction for ovarian stem cell research and help women with fertility conditions," he said.
The findings of the study have been published in the July issue of Reproduction.