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The Growth of a Hair

Each hair follicle is genetically programmed before birth to either become sensitive to the male hormones that begin to appear during puberty – causing the follicle to eventually shrink and die – or to not become sensitive and continue growing throughout life.

Every single hair on the scalp grows for two to six years, remains for a time, and then falls out. In fact, every day one loses 50 to 150 hairs. When a hair falls out, a new hair begins growing in its place. Sometimes, testosterone affects this normal growth cycle. Hair follicles, the tiny cup-shaped structures from which hairs grow, start to shrink. In men, this only happens on the front and top of the scalp since the back and sides are programmed to grow for life. In women, hair loss is spread out over the scalp while retaining the natural hairline in many cases.

As the follicles shrink, the resulting hair is thin and sparse. Eventually the follicles shrink to the extent that new hair cannot grow. The result is male or female pattern baldness.


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