In a series of experiments on sterile female mice, Massachusetts General Hospital (MGH) researchers were able to restore egg production by transplanting bone marrow from fertile mice. The researchers believe that egg stem cells in the donor bone marrow established themselves in the sterile mice and began producing egg cells. The results are published in the July 29, 2005 issue of Cell.

The research team treated mice with a chemotherapy drug known to destroy eggs but to be less damaging to long-term fertility, and found the ovaries lost 80 percent of their egg cells within 24 hours. Within two months, the ovaries appeared to have fully recovered.

To find the source of egg replenishment, they examined the ovary for a molecule found only on the surface of cells that develop into eggs in the embryo. They found a part of the ovary where blood enters and exits but is devoid of egg cells.

On examining the bone marrow, they found several proteins created only by reproductive cells and by cells developing into reproductive cells.

To test whether they had found the egg stem cell site, they transplanted bone marrow into chemically and genetically sterilized mice. Both sets of mice began growing egg cells in their ovaries.