The Sweet Hair After
Future Hair-Loss Treatments Promise What's not Hair Today will Be Hair Tomorrow.
What We Know About Hair continued...
Hair growth goes through several distinct stages:
Anagen. The growth phase of hair. An unknown signal tells follicle
stem cells to do their thing. Next, the permanent part of the follicle -- the
dermal papilla -- gives the "go" signal to hair matrix cells. Those
cells grow wildly and become pigmented, creating a new hair shaft. At any given
time, 90% of hair cells are in this stage.
Exogen. The new hair shaft pushes the old, dead hair shaft out of
the skin. The old hair falls out.
Anagen finished. The new hair extends beyond the surface of the skin
and keeps growing. The hair shaft fully matures.
Catagen. The lower two-thirds of the follicle shrivels up and is
destroyed. The dermal papilla remains attached to the regressing follicle.
Telogen. The withered follicle rests. It waits for a signal telling
it to start all over again.
Losing hair is part of a normal cycle of growth and
replacement. Hair follicles go through the growth and resting cycle in a
nonsynchronized fashion. But sometimes things go wrong.
Common Hair Loss Problems: Androgenetic Alopecia
Most of us, when we think of hair loss, think about aging men.
Nearly all men eventually get that receding M-shaped hairline and thinning hair
on the top of the head, also known as male pattern baldness. It's called
androgenetic alopecia, and it's caused by a by-product of testosterone called
Aging women have a similar problem. Their hair gets thin,
although it's not clear that this is necessarily caused by sex hormones.
What is clear is that the same thing happens in aging men and
women. Hair follicles get smaller. The anagen stage of hair growth gets
shorter, and the resting (telogen) stage gets longer. The result: Thin, very
short hairs -- and many follicles empty of hair shafts.
Why is this pattern of hair loss only in the front and on top?
That's where hormone-sensitive follicles live. The follicles on the sides and
back of the head aren't affected by DHT and usually stay healthy.