Chapter 6.2, Problem 2AYLO

Three kinds of hair, including fetal and adult types

INTRODUCTION:

Hair is a slender filament grows from hair follicle made up of keratinized cells.

EXPLANATION:

There are three kinds of hair including fetal type and adult type. They are

1. Lanugo

2. Vellus

3. Terminal hair

Lanugo:

They are fine, downy, unpigmented hair which appears on the fetus in the last 3 months of fetal development. After birth, most of the lanugo is replaced by vellus hair.

Vellus:

The vellus hair is the fine, pale hair which replaces lanugo by the time of birth. It presents except on eyebrows, eye lashes and hair of the scalp. It is seen two third in women, one tenth of men and all over in children.

Terminal hair:

These are the longer, coarser and more pigmented type of hair. These type of hair forms eyebrows, eyelashes and scalp. It is also seen in axilla and pubis after puberty.

CONCLUTION:

Hairs are seen in everywhere in the body except palms and sole. The density and pigmentation differs in male and female.