Definition: A hair follicle is a stocking-like structure that contains several layers with different jobs. At the base of the follicle a projection is formed like sticking a finger in the bottom of a stocking and pushing it in a small amount. This projection is called the 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 by the capillaries. The cells in the bulb divide every 23 to 72 hours, faster than any other cells in the body.
