(excerps from the Journal of Electrology volume27 A.E.A)
…depends on whether the follicle is sensitive to these hormones. Some skin areas; eyelashes, eyebrows, some aspect of the scalp appear to be relatively resistant and independent of the effects of androgens and are designated as non-sexual skin areas.
Other areas, including the lower pubic triangle and the axilla (underarm) are very sensitive to the effects of even low level of androgens because of their high action of 5â reductase activity and are designated as ambosexual skin areas. The hair follicles in these areas develop terminal hairs quite early in puberty, coinciding with the minimal increases in adrenal (glands above kidney) androgens.
Other parts of the skin contain lower level of 5â-reductase and respond only to higher concentration of androgens. These include the chin, cheek, sideburn, and neck area, the upper and lower abdomen, the upper thighs and buttocks, the upper arms.
These areas are designated as sexual skin areas.
Terminal hair growth in these areas is characteristically masculine and, if present in women is considered hirsutism.
The experts say, that there is not much difference in follicles’ number between sexes within each race and ethnics groups, but rather the type of hair arising from those follicles (vellus/fine hair versus terminal/dark hair).
In women, many of the hair follicles produce vellus hairs, in men these same follicles produce terminal hairs; visible facial, chest, and abdominal hair.
Androgens also transform vellus-producing follicle to terminal hair-producing follicle, an irreversible process.
Hair is there to protect the skin and derma irritation particularly in the face, can stimulate hair growth. Excessive waxing or tweezing, abuse of depilating agents and some acid for treatment of age-related wrinkles, have all been reported to increase the length and diameter of facial hairs and possibly convert vellus to terminal hairs.
“Not to know is bad, not to wish to know is worse”.