Follicular miniaturization is described as
the conversion of large hairs into finer ones,
which in turn leads to the balding process
otherwise known as androgenic alopecia. It
is the major occurrence of hair loss pattern.
There are certain types of hair found on human
skin. These are:
- Vellus hairs, or finer, smaller hairs – the
growth of which is not due to hormonal
- Terminal: large, thick ended
hairs which are highly pigmented and usually
the scalp, beard, armpits and pubic area. The
growth of which, is due to hormonal influence.
- Intermediate hairs, thin hairs which
can be classified as somewhere in between
In utero, the fetus is covered with long
lanugo. These are fine downy hair found among
infants. Lanugo covers the fetal forehead
like that on the scalp. By the fifth month,
the lanugo begins to diminish and involute.
Vellus hairs are widespread on children’s
scalp but seldom grow in later teenage years
and then resurface in the twenties. This could
be due to the adaptation to terminal hairs.
Because of aging, hairs of both men and women
go through successive miniaturization and
thus terminal scalp hair density is lessened.
Miniaturization in Androgenetic Alopecia
The hair follicle is a very interesting subject.
Knowledge of its anatomy is practical in understanding
the development of hair miniaturization. On
the average, there is an approximate of 100,000
human hairs on an adult scalp. Ninety percent
of which are in the growth or anagen phase,
where as the ten percent belong to the resting
state or telogen. Anagen’s average age
ranges to 1000 days, telogen’s to 100
days with the average loss of 100 hairs per
day. This percentage is well distributed over
the whole scalp.
In lieu of androgens, genes cut down when
the anagen phase is stimulated and hair follicles
miniaturize. Progressive anagen cycles make
follicles become short and fine. Pigmented
terminal hairs then are substituted by non-pigmented
In pattern baldness, as time progresses,
the papillae and matrices of hairs together
with the resultant hair shafts become gradually
altered by miniaturization. This results to
a fewer terminal-to-vellus hair ratio of normally
at least 2:1. Previously, it was thought that
this conversion of terminal to vellus slowly
regenerated over a number of follicular cycles.
But some researchers and biologists agree
that it is improbable that the miniaturization
can be caused only by a sequence of short
Evidences show that the development would
lead to a longer duration for considerable
miniaturization to happen secondary to shorter
anagen cycles by itself. Particularly in relation
to the latent lag period witnessed in patterned
hair loss that take place between the loss
of telogen hair and the surfacing of an anagen
hair. Hair experts believe that miniaturization
is fast, but the large phase process can also
be reversed in a certain hair cycle. This
concept is maintained by verified histological
proof in patients with pattern hair loss in
response to finasteride, a drug used to lessen
the number of testosterone in the body. It
is proposed that miniaturization, as seen
with pattern hair loss could have been caused
by the decline in the number of cells and
thus, the size of the dermal papilla.
Studies reveal that the beginning of miniaturization
may happen at some phase in early catagen
or early anagen. This is when the dermal papilla
shifts up or down the temporary lower follicle
and is subject to outside factors. Supposing
miniaturization does not take place in established
anagen, anagen hairs may continue a similar
diameter during each hair cycle, nor in telogen
where there have been found no metabolic activity.
Where does follicular miniaturization take
Miniaturization takes place in the dermal
papilla and the dermal sheath or the perifollicular
sheath of the hair follicle when released
by the stem cells in the follicular bulb.
The dermal papilla is the connective tissue
component that is covered by the bulb of the
follicle in anagen phase, which forms a condensed
ball of dermal cells beneath the “hair
germ” in telogen.
According to hair experts, this terminal
to vellus exchange is manipulated by androgen
receptors, 5a-reductase, stem cell factors,
drug factors and cytokines. Fibrous tracts
continue subsequent follicular miniaturization.
Miniaturization of Hair in Male Androgenetic
All hair in an affected area may in the long
run lead to the miniaturization process and
in time could cover the site with fine vellus
hairs in men with pattern baldness. Since
pigment production also comes to a halt with
successive miniaturization, the site may soon
appear bald long before the vellus hair externa
is finally gone. With the progression of this
condition, the involved areas can then be
totally denuded of hair.
Miniaturization of Hair in Female Pattern
The extent of miniaturization of hair is
not consistent nor is it a probable extreme
in a given area of scalp in women. Rather,
women with pattern hair loss have a mixture
of variable-diameter hairs in the involved
area of the top of the scalp. This clarifies
the distinction in the clinical signs between
men and women. In women with female pattern
hair loss, there is an obvious reduction in
hair volume in the involved region, contrary
to baldness in men. In severe cases of women
with pattern hair loss that becomes bald,
estimation for a primary pathologic hyperandrogen
state is significant.