|
Pubic hair is hair in the frontal genital area, the crotch, and sometimes at the top of the inside of the legs; these areas form the pubic region. Although fine vellus hair is present in the area in childhood, the term pubic hair is generally restricted to the heavier, longer hair that develops with puberty as an effect of rising levels of androgens on the skin of the genital area. Pubic hair is therefore part of the androgenic hair.
Development of pubic hair
Before puberty, the genital area of both boys and girls has very fine vellus hair, referred to as Tanner stage 1 hair. In response to rising levels of androgens as puberty begins, the skin of the genital area begins to produce thicker, often curlier, hair with a faster growth rate. The onset of pubic hair development is termed pubarche. The change for each hair follicle is relatively abrupt, but the extent of skin which grows androgenic hair gradually increases over several years.
In most girls, pubic hair first appears along the edges of the labia majora (stage 2), and spreads forward to the mons (stage 3) over the next 2 years. By 3 years into puberty (roughly the time of menarche for most girls), the pubic triangle is densely filled. Within another 2 years pubic hair also grows from the near thighs in most young women, and sometimes a small amount up the line of the abdomen toward the umbilicus.
In boys, the first pubic hair appears as a few sparse hairs on the scrotum or at the upper base of the penis (stage 2). Within a year, hairs around the base of the penis are too numerous to count (stage 3), and within 3 to 4 years, hair fills the pubic area (stage 4), and by 5 years extends to the near thighs and upwards on the abdomen toward the umbilicus (stage 5).
Other areas of the skin are similarly, though slightly less, sensitive to androgens and androgenic hair typically appears somewhat later. In rough sequence of sensitivity to androgens and appearance of androgenic hair, are the armpits (axillae), perianal area, upper lip, preauricular areas (sideburns), periareolar areas (nipples), middle of the chest, neck under the chin, remainder of chest and beard area, limbs and shoulders, back, and buttocks.
|
