Researchers in Boston, USA, are apparently overturning the accepted fact that women are born with all the eggs they will ever have and gradually lose them over the period of their fertile life.
It appears that mice continue to produce new eggs from stem cells after birth. However, the research has yet to be proven in humans, although if this does happen it may have far-reaching consequences for women’s fertility.
Examination of the ovaries of mice of all ages showed cells on the outside of the ovary that resemble the cells that are the source of eggs in foetal animals. What the team have done is to demonstrate that egg cells develop and form new follicles within the ovarian tissue in genetically altered mice.
The team have suggested that the decline in fertility in women after the age of 30 might be the result of the depletion of these stem cells rather than reducing numbers of eggs. At present the team are trying to isolate the cells so that they can be stored and then used in investigations about ovarian failure and infertility.
(Nature, March 10, 2004)