Colin Jahoda, a scientist at Durham University who used his wife, Dr Amanda Reynolds, as the guinea pig, said the findings open the way to new treatments for hair loss and plastic surgery.
"This is the first step towards a treatment for baldness," said Dr Jahoda. "It is the first time in humans we have been able to use donor cells to teach the recipient cells to grow hair."
Skin surgeons dissected small fragments of skin from Dr Jahoda's scalp and implanted the cells into the inner surface of Dr Reynolds' forearm. To their surprise, the male tissue was not rejected and began to induce hair growth.
"The fact that my wife grew hair which was a different colour and type to her own means the two cell types must have been interacting," added Dr Jahoda. "There's a long way from this to a full head of hair but the principle is there.
"It may be some time before the cells can be manipulated to create something cosmetically acceptable, a particular hair type and colour."
Genetic tests of the follicle cells from Dr Reynolds' arm confirmed they had both female and male chromosomes. So some, but not all, of the cells in the new hair follicles must have come from Dr Jahoda.
The scientists tried to minimise the chances of tissue rejection - almost inevitable when transplanting living cells from one person to another - by repeatedly washing the scalp tissue to remove other cells that may interfere with a successful graft.
"But the main reason why the graft was not rejected probably lies with the tissue itself," the scientists say. They think hair follicles have a special "immune status" which may prevent tissue rejection. They believe just a few hundred cells of the scalp skin were enough to induce the growth of new follicles in the skin of an unrelated person of the opposite sex.
The tissue grafts healed rapidly and new follicles formed within three to five weeks, producing the large, thick hairs of the scalp rather than the small, unpigmented "velus" hairs which normally grow on a woman's forearm.
Dr Reynolds has had all the tissue grafts removed for analysis. Dr Jahoda said: "None of the new follicles showed much evidence of rejection when biopsied between 41 and 71 days after the graft.
"The results could also be of future benefit in research on creating replacement skin, for example, for burn victims. One might envisage being able to produce skin that is more complete, that had hair follicles."
Dr Jahoda said his wife first spotted the new hair. "She covered it up to protect it and gradually it grew," he added. "The really creative part of the work came from my wife. She had the vision to think up this experiment." Dr Reynolds, 35, is an honorary research fellow at Durham.
Dr Jahoda said more studies with volunteers will be needed to see if the lack of tissue rejection is a universal phenomenon rather than a one- off affair between husband and wife.Reuse content