Terminal Hair

The Hair That Appears During Puberty

Adolescent students.
Adolescent students. Hero Images/Getty Images

Terminal hair is the thick, long, pigmented hair found on the scalp, face, armpits and pubic area. The growth of terminal hair is influenced by hormones.

Hair Follicles

There are hair follicles all over the body. Within the follicles are stem cells, blood vessels, sebaceous glands and, of course, hair. The follicle lies within the second layer of the skin: the dermis. This is the living part of the hair.

The outer hair - that is, the hair you can see - is actually dead.

Aside from the palms of the hands, the soles of the feet and the mucous tissues, the entire human body is covered with vellus hair. Vellus hair, often called peach fuzz, is thin, short and light-colored. Unlike terminal hair, the growth of vellus hair is not influenced by hormones.

Terminal Hair Growth

During puberty, increased hormone levels cause vellus hair to turn into terminal hair in certain parts of the body. Different parts of the body possess different levels of sensitivity to these hormones, known as androgens.

Androgens are known as male hormones because males produce and use androgens, like testosterone, more than females. Although these supposed "male" hormones are present in females - they play a lesser role - they are essential in male physical and sexual development.

Parts of the body that respond to these hormones include the pubic area and the armpits, which occurs in both males and females.

Females keep more of their vellus hair, while males develop terminal hair in more parts of the body, including, but not limited to the face, chest, back, legs, arms, hands and feet.

Stages of Hair Growth

Puberty typically begins in boys between the ages of 9 and 15, and in girls between ages 8 and 14.

In males, terminal hair appears throughout the teenage years, although where the hair appears changes. In the early stages of puberty, terminal hair growth is concentrated in the pubic area and armpits. Some facial hair appears early on, but it fills in during the final stages of puberty, typically by the early 20s. Females can expect to develop thicker leg hair and terminal hair in the pubic area and armpits during their teens.

Terminal hair growth doesn't always occur as it should. The pituitary gland secretes hormones that initiate puberty, including the Luteinizing hormone, androgens and progesterone in females. If these hormones aren't being secreted, puberty cannot occur.

In some cases terminal hair begins to grow earlier than normal. The exact cause for premature puberty in males and females can't always be identified, but it's been linked to hormonal disorders and exposure to external hormones (estrogen and testosterone) through something like a topical ointment. In other cases, terminal hair doesn't grow.

Genetics are most often to blame, but it's also caused by diabetes, kidney disease, asthma and abnormalities in the thyroid and pituitary gland.




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