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Baldness Biology
 Male pattern baldness overview
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 Hair fiber in pattern baldness
 Hair follicles in pattern baldness
 Androgen hormones in men
 Androgen hormones in women
 Androgen receptors in baldness
 5 alpha reductase in baldness
 Inflammation in baldness
 Genetics in pattern baldness
 Diseases associated with baldness
 Pattern baldness in children
Baldness Treatments
 Minoxidil for pattern baldness
 Minoxidil for female baldness
 Minoxidil for male baldness
 Finasteride for male baldness
 Finasteride for female baldness
 Tretinoin for pattern baldness
 Diazoxide for pattern baldness
 Ketoconazole for pattern baldness
 Antiandrogens for pattern baldness
 Contraceptives for female baldness
 Spironolactone for female baldness
 Flutamide for female baldness
 Cyproterone acetate for baldness

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 influence.
  • Terminal: large, thick ended hairs which are highly pigmented and usually found on 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 vellus and terminal.

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 vellus hair.

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 anagen cycles.

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 place

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 Alopecia

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 Hair Loss

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.

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