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09/25/2001
Hair
After the events of the past two weeks, I was having trouble with
both getting in the mood to write a column and trying to come up
with a suitable topic. Then I got an e-mail from my witty friend
Dan in Hawaii. In it he said, "In the past I have been sort of
''frivolous'' in my letters to you - but this does not seem to be the
time for frivolity." I certainly could not agree more with that
sentiment. But then I couldn''t help thinking of the words of our
Mayor Giuliani when he suggested that we should return to our
normal routines. I say ''our'' Mayor even though I''m not a New
Yorker but in a sense isn''t he everyone''s Mayor today?
Following his advice, shouldn''t a frivolous topic be appropriate?
I was sitting here, debating whether to start my column or walk
downtown to get a haircut, when I recalled an article by Ricki
Rusting in the June 2001 Scientific American. The article was
titled "Hair. Why It Grows. Why It Stops." When I look in the
mirror in the morning, I see what looks like pretty good head of
hair for a man my age. However, when I take another mirror and
look at the back of my head, there is quite an appreciable and
growing bald spot. What could be less important in today''s
climate than hair? At the same time, for many the loss of hair is
a serious matter, perhaps most notably when it occurs as a result
of chemotherapy. Hair as a topic seems suitably frivolous yet, to
many, sufficiently serious to warrant discussion in these troubled
times. According to the Scientific American article, it''s been an
exciting time in the search for and understanding of how hair
grows and what factors influence its growth and loss.
Hair comes in many forms - fur, bristles, a cat''s whiskers, a
porcupine''s quills, a sheep''s wool, etc. Hair is rich in keratin, the
same type of stuff that makes up our fingernails and the feathers
of birds. Each one of our hairs has a root and a shaft. The root
and a bit of the shaft are below the skin in a follicle. It''s in the
follicle that the action takes place. The shape of the follicle
determines whether your hair is straight or curly - if it''s cross
section is round, your hair is straight; if it''s flattened, your hair
is curly. If you''re typical, you have about 100,000 follicles on your
head. A blond has around 140,000 hairs, a brunette about
105,000 and a redhead only about 90,000 according to my 1962
edition of The World Book Encyclopedia.
We generally come into the world with 5 or 6 million follicles
distributed over our body except on the palms of our hands and
soles of our feet. Otherwise, on those areas where we may not
think we have hair, there are very fine short hairs that we don''t
normally notice. There are tiny muscles linked to each follicle
that can make the hair "stand on end". This effect is more
evident in certain animals where the hair visibly does seem to
stand on end. We''re more likely to experience the simultaneous
firing of these muscles to give us goose bumps. The life of one
of our hairs depends on its location. A hair on our head may
grow for several years before it falls out while an eyebrow hair
lasts only a couple months before a new hair replaces it. All the
hair that we encounter above the skin is composed of dead cells.
Could that be why it doesn''t hurt to get a haircut?
Why am I telling you about hair anyway? If it''s mostly just a
bunch of dead cells, what''s so interesting? It''s time to go deeper,
into the follicle. The hair follicle is something like a long bud
vase with a bulb on the bottom. However sticking up into the
bottom of the bulb is something that resembles the head of a
sperm cell - this is the dermal papilla. Let''s call it DP for short.
DP turns out to be sort of a command center in charge of the
growth of hair in that follicle. There''s another feature of the
follicle that comes into play. Up near the surface of the skin,
there''s a bulge in our bud vase or follicle. This bulge attaches to
the muscle and above the bulge there''s what the World Book
calls a fat gland. Of course, these days we call it a sebaceous
gland. Here we don''t have to worry about this gland, just about
the DP and the bulge.
Hair growth in a follicle is a process that goes in cycles, each
cycle having three phases. These phases are called catagen,
telogen and anagen, none of them known to my spellchecker!
I''ll replace these fancy terms with decay, rest and growth. I''m
going to skip some of the details in this cycle but let''s start with
the decay phase. We have a hair that''s been growing in the
follicle. The root of the hair is sort of wrapped around the DP. In
decay, the cells between the DP and the bulge essentially commit
suicide, leaving behind decaying cells. Now there''s nothing
between the DP at the bottom of our follicle and the bulge up
closer to the surface of the skin. There''s a difference between a
bud vase and a follicle. The wall of the follicle isn''t made of
glass but is a membrane that is flexible and acts like a stretched
rubber band in that it collapses and pulls the DP up to the bulge.
In the process, the root and the hair below the bulge have
disintegrated and the remaining hair has no anchor. As a result,
it''s ripe for falling out. In our scalp, this whole decay phase took
about two weeks.
Now we''re in the second phase, the rest phase. What''s left of our
follicle just sits around doing nothing for maybe three months or
so. The remaining hair may fall out or wait until the third phase,
the growth phase. The length of time our follicle rests can be
influenced by various factors. For example, plucking out that
hair may shorten the rest time.
Ok, we''ve rested long enough. Now what? Here''s where that
bulge comes into play. The bulge isn''t just an architectural foible
but turns out to be a storehouse containing a supply of those
much-talked about stem cells. These stem cells start to divide
and form several types of cells. Some of these cells have the job
of reconstituting the lower part of the follicle. Our follicle goes
back to its original size and shape with the DP dropping back to
the bottom. Another type of cells derived from the stem cells is
known as ''matrix'' cells. Once everything is back in place, the DP
tells these matrix cells to get cracking and start growing hair
again. As the new hair grows any old hair that didn''t fall before
is pushed out.
In our scalp, this new hair will grow at about a half inch a month
for typically 6 to 8 years. For a young adult, maybe 90 percent
of the follicles are growing hair while about 10 percent are either
resting or in the decay mode. In a day, he or she will lose around
50 to 100 hairs. Why do people go bald or suffer thinning hair?
It''s not because you lose any follicles. Instead, it''s because there
are more of those lazy follicles just lolling around doing nothing
in their rest periods. There are also more follicles in the decay
phase. Also follicles may shrink with aging. This results in the
production of small fine hairs - you didn''t really lose that hair,
you just can''t see it!
I mentioned the excitement for those working on hair. The past
few years have seen the identification of the fundamental
mechanisms of hair growth. When I glibly said that the DP tells
the matrix cells to get cracking, I glossed over the complex
chemistry that accomplishes this process. I don''t profess to begin
to understand it but researchers are zeroing in on the proteins that
regulate the hair growth and have run experiments on mice to
check out these proteins. By withholding or adding certain
proteins workers can grow mice with really lush hairy coats and
even make new follicles. That''s the good news. The bad news is
that in humans the same proteins may cause the growth of tumors
or promote various forms of cancer.
However, when the exact nature of the proteins and their
interactions is pinned down, the hope is to be able to come up
with a drug that will get those lazy resting follicles off their duffs
and back to work. Meanwhile, those wishing to obtain a
modicum of restored hair growth will have to rely on the drugs
minoxidil or finasteride. For some people, these drugs provide
enough regrowth of hair to warrant their continued use.
Back to more serious things, wouldn''t it be great if the spirit of
New York and the country turns around and follows the same
upward path as those amazing New York Mets? Odds are they
won''t make it from the bottom to the top but they''re sure giving it
a New York try. Now if Mike Piazza will only promise not to
ever again dye his hair yellow!
Allen F. Bortrum
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