The recent revelation that female muscle cells work better than male muscle cells came when researchers at the University of Pittsburgh Medical Center were injecting muscle stem cells into mice with a disease similar to muscular dystrophy to see if the cells would regenerate damaged skeletal muscle. They did. Then the scientists noticed something they didn't expect: the stem cells taken from healthy female mice produced far better results than stem cells taken from male mice.

These are not embryonic stem cells that can grow into any cell in the body; these are adult stem cells that are limited in their ability to grow into just muscle cells.

"Regardless of the sex of the host, the implantation of female stem cells led to significantly better skeletal muscle regeneration," the study's senior author, the University of Pittsburgh's Johnny Huard, told MSNBC.

This is yet another blow to us men, coming on top of the news that the Y gene is shrinking and that men continue to die younger than women. Now it appears that our usefulness for providing certain stem cells may also be in doubt. It makes me wonder what will come next in this molecular biobattle of the sexes.

The University of Pittsburgh Medical Center study was published in the April 9 issue of the Journal of Cell Biology.