This new theory, which has been put forward by researchers at the Massachusetts General Hospital, if confirmed, will have major implications for fertility treatments. However, this research still has many critics.

The researcher team, which is led by Jonathan Tilly, reported in Cell that this "cache" of germ-line stem cells in the bone marrow send cells by way of the blood stream, directly to the ovaries. Furthermore, they then signal to the marrow when further supplies of germ cells are needed.

The work Tilly and his team are doing involve mostly experiments with mice. However, they also cite instances where women have received bone marrow transplants after chemotherapy and unexpectedly conceived. The researchers are suggesting therefore, a new supply of oocyte-making cells from the new bone marrow can affect overall fertility.

If this theory proves to be true, this would further reinforce the idea that the bone marrow is the repository of the body's regenerative capabilities.

As we all already know, blood cells are renewed from stem cells in the marrow. We also know that the bone, cartilage and fat cells can be derived from bone marrow stem cells. Even further, some researchers believe the heart is renewed by cells from the marrow.

Tilly's research would now add the reproductive system to this list.

This idea has not yet won acceptance, however, among other researchers in the field. At a in Quebec of the Society for the Study of Reproduction, Dr. Tilly debated his theory with David Albertini of the Kansas University Medical Center.

Dr. Albertini said the general reaction of his colleagues to Dr. Tilly's theory was "overwhelmingly negative."

Dr. Tilly, however, said that although Dr. Albertini had canvassed several laboratories working on the problem, none of the researchers had reported any results which would disprove the theory. "There was nothing presented that refuted our work," Dr. Tilly said.

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