The research conducted at the Massachusetts General Hospital involved bone marrow transplantation given mice following fertility-destroying chemotherapy.

The researchers said their findings support a study that showed donor marrow can restore fertility in female mice through an as-yet unidentified mechanism. While donor-derived egg cells or oocytes were observed in the ovaries of marrow recipients, all pups born were from the recipients' own eggs.

"Consistent with our past work, cells derived from the donor bone marrow are getting into the ovaries and developing into immature oocytes," said Jonathan Tilly, director of the hospital's Vincent Center for Reproductive Biology and the study's senior author. "Although these oocytes derived from marrow cells don't appear competent, at least thus far, to make fertilizable eggs, marrow does contribute something that allows a resumption of fertility in female mice sterilized by chemotherapy."

Previous research by Tilly's group was extremely controversial and the current study was designed to address criticisms raised by other researchers.

The latest investigation is reported in the Journal of Clinical Oncology.