One group theorize that this special stem cell lives in the "bulge" of the hair follicle, near the top of the skin pore, he explained.
Others (including this research team) believe the elusive stem cell can be found at the base of the hair shaft.
Still others throw out both hypotheses, arguing instead that skin cells can replenish themselves.
These researchers, based at different European institutes, showed that cells marked by the Lgr6 gene and located in the hair follicle are the original mothers (or fathers) of other skin cells.
They were also able to show that, in mice, these Lgr6 genes could repair skin and produce new hair.
But while these earliest cells continued to produce sebacious glands and interfollicular epidermis, their contribution to hair growth gradually diminished over time.
"This might provide more insight into understanding why skin ages and hair changes as we age," Sanberg said. "Clearly, understanding these kinds of stem cells is important because it could impact methods of wound healing as well as cosmetics."
But, Eggan said, the paper is unlikely to be the last word in the dispute over which stem cell came first.
The U.S. National Institutes of Health has more on stem cells.
SOURCES: Kevin Eggan, Ph.D., chief scientific officer, The New York Stem Cell Foundation, and associate professor, stem cell and regenerative biology, Harvard University, Boston; Paul Sanberg, Ph.D., D.Sc., distinguished professor of neurosurgery and director, University of South Florida Center for Aging and Brain Repair, Tampa; March 12, 2010, Science
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