Scientists say hair loss may soon become reversible, as they've found that a single gene can encourage hair growth:
The human head comes equipped with 100,000 tiny hair follicles, from each of which grow a single hair.
These follicles are produced by the embryo in the first stages of pregnancy, and it was thought that no further replacement follicles could be produced during life.
The Pennsylvania team found that a particular gene important in wound healing, called wnt, appeared to play a role in the production of new hair follicles.
In its experiment, small sections of the outer skin layer, or epidermis, were removed from mice.
Just this act appeared to awaken stem cell activity in the area, the scientists said, which included the production of a number of hair follicles.
If the action of the wnt gene was blocked, no hair follicles were produced; but if it was boosted, then many more hair follicles were produced, with the skin layer eventually being indistinguishable from surrounding areas.