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If any of the stages of hair growth are disrupted, the individual may become bald. For example, if follicles shut down (meaning that they stay in the resting phase, and then shed the hair) instead of growing new hairs, there will be less hair on the head. Another reason might be interference with the formation of new hair cells at the root during the growing phase.
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If follicles have been destroyed (ie., a burn, loss of layered skin or trauma), there will be baldness in that area. An individual can also look bald if the hairs are growing but are so fragile that they break just as they emerge from the follicle. Recently, scientists announced the discovery of a gene that appears to be the 'master switch' for male hair growth. They found the gene after comparing the genes of hairless mice belonging to a mutant breed, and comparing the genes of 11 members of a family who had lost all their hair. This discovery is a step towards understanding how the hair follicle works and how baldness happens, and may lead to effective treatments becoming available in the future.
Receding hair is loss of hair at the sides of the forehead. It happens to most men eventually - usually at or after middle age, but it can start at any time after puberty. Some men also have loss of hair on top of the head, and eventually only the sides and back of the head have hair, forming a horseshoe shape. |
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| This is known as common baldness, androgenic alopecia or male-pattern
Surprisingly, if you were to view a balding scalp under a microscope you would see that there are the same number of hair follicles as before, but each is shrunken, producing hairs that are fine, short and pale.
You would also note that a higher proportion than usual of the follicles are in the resting phase. Three factors are at work in male-pattern baldness: male hormones, genetics and ageing.
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