Reactivating dormant stem cells in the scalp could help hair to grow back, scientists believe.
Researchers made the discovery after examining tissue sample from bald men undergoing hair transplants.
Comparing follicles from bald and hairy scalp patches, they found that both contained the same number of stem cells, but that a type of more mature cell called a progenitor was lacking in the bald areas.
Stem cells in the scalp normally develop into progenitor cells, which in turn give rise to new hair growth. But those from the bald patches appeared to have become dormant.
The research suggests that male