A developing fetus has all of it's hair follicles formed by week 22. Truth be told there are 5 million follicles on your body. One million of those are on the top, and 100,000 take presctiption the scalp. This is the largest range of follicles we will ever have - follicles will never be added during life. For the reason that size of the body increases as the years accrue, the density of the the hair follicles on the skin decreases.

Hair has two separate structures - the follicle inside skin and the shaft we see.

Follicle - The follicle is really a stocking-like structure that contains several layers with some other jobs. At the base of the follicle is a projection formed like sticking a finger in the bottoom of a stocking and pushing it in a tiny amount. This projection is named a papilla and it contains capillaries, or tiny blood vessels, that feed the cells. The living part of the hair is bottom part of the stocking surrounding the papilla called the bulb. This bottom part is the only part fed through the capillaries. The cells in the bulb divide every 23 to 72 hours, faster than almost every other cells in the body.

The fllicle is between two sheaths - an inner and outer sheath. These sheaths protect and mold the growing hair shaft. The inner sheath follows the hair shaft and ends below the opening of a sebaceous (oil) gland, and often an apocrine (scent) gland. The outer sheath continues up up to the gland. A muscle called an erector pili muscle attaches below the gland to a fibrous layer around the outer sheath. If this muscle contracts, it causes the head of hair to stand up.

The sebaceous gland is essential because it produces sebum that is a natural conditioner. More sebum is produced after puberty. The sebum production decreases in women throughout their lives. The production also decreases in men, but not as much as in women.

Shaft - The hair shaft is made up of dead, hard protein called keratin in three layers. The inner layer is referred to as the medulla and may not be present. Our next layer is the cortex and the outer layer is the cuticle. The cortex balances out the majority of the hair shaft. The cuticle is actually created by tightly packed scales within an overlapping structure similar to roofing materials. Most hair conditioning products make an effort to affect the cuticle. There are pigment cells which might be distributed throughout the cortex and medulla giving the head of hair it's characteristic color.