New eggs from old mice?

© Andy Walker / Photo Researchers, Inc.

The paper:

The finding:

Jonathan Tilly, director of the Vincent center for reproductive biology at Massachusetts General Hospital, and colleagues showed in 2005 that mice sterilized by chemotherapy or lacking a key gene for making oocytes could be prompted to develop immature oocytes after bone marrow transplantation.

The controversy:

Subsequent studies appeared suggesting that bone marrow stem cells couldn't possibly produce mature fertilizable eggs, and Tilly had to counter claims that he overinterpreted results.

The new finding:

Now, an in-press study in the Journal of Clinical Oncology reveals that in a mouse model of chemotherapy-induced ovarian failure, bone marrow transplant restored fertility. But, the offspring are not derived from donor stem cells.

The optimism:

Tilly says he's excited, "But we're also at a roadblock in that the germ cells haven't been able to fulfill the ultimate goal, which is to make a baby."

The relevance:

Whether their findings will have clinical relevance to infertility is debatable, says John Eppig at Jackson Labs, but such work could inform gametogenesis: "In the end, we're probably going to learn a lot about the essence of what it is to be an oocyte and what it takes to get there."