Except for its dermal papilla which contains connective tissue and blood vessels, the rest of the hair follicle is composed of epidermal cells. The bulb, at the lower end of the hair follicle, is the thickest part. It contains the proliferating pool of undifferentiated epidermal cells. Differentiation begins at the constriction above the bulb and continues halfway up the follicle where the cells begin to cornify. The hair is fully hardened as it emerges from the skin surface.
Human hair grows in cycles.
The longer the hair growth phase of an individual, the longer the hair length is. The growing stage is called anagen, followed by a transitional stage termed catagen, during which hair growth slows-down. This stage is followed by the resting phase, telogen. Once a hair has gone into telogen it is eventually shed and a new hair forms in the same follicle. Hairs do not cycle together, therefore there is a daily loss of hairs throughout the entire scalp.