Stem Cells Stimulate Egg Development in Adult Mice

Production of offspring from a germline stem cell line derived from neonatal ovaries.

Zou K, Yuan Z, Yang Z, Luo H, Sun K, Zhou L, Xiang J, Shi L, Yu Q, Zhang Y, Hou R, Wu J.
School of Life Science and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China.

Nat Cell Biol. 2009 Apr 12

During embryonic development in human females and most mammalian species, cells in the ovary called oogonia proliferate by numerous mitotic divisions to form primary oocytes. About one million form per ovary. These begin the fist meiotic division and then stop before the birth of the female in a prolonged diplonema stage called the dictyotene. A primary oocyte does not resume meiosis until the female is past puberty, when under hormonal control, ovulation takes place. This process usually occurs for only one oocyte per month during the female’s entire reproductive lifespan (from twelve to fifty years of age). The first meiotic division is completed and this is followed by the second meiotic division, thus completing the process of gamete formation in the female.

However, the idea that females have lost the capacity for oocyte production at birth has been challenged by this article which gives evidence for the existence of female germline stem cells (FGSCs) in postnatal mammalian ovaries. The authors have isolated FGSCs from young and adult mice and cultured them for more than 6 months. These FGSCs were infected with a green fluorescent protein (GFP) virus and transplanted into ovaries of infertile mice. Eighty percent of these mice went on to produce offspring that had the GFP transgene after natural mating.

This finding, if corroborated by other researchers, may help infertile women conceive and have children. A question that comes to mind is: do infertile women have FGSCs in their ovary? If the answer is “yes”, how can they be stimulated to undergo oogenesis? On the other hand, if the answer is “no”, then treatment will involve transplantation of FGSCs from a donor to the infertile recipient, in which case immunosuppression may be required to prevent rejection. Another possible application would be in prolonging the reproductive lifespan of women. Generation of new oocytes could help older women conceive. In addition, it could be a boon for those with premature ovarian failure.