The epidermis is formed by layers of flat cells composing a stratified squamous epithelium.
New cells originate in the lowest layer and become keratinized as they are pushed to the surface.
Keratin is a fibrous protein that also forms the substance of hair, horns and hoofs. At the ultrastructural level it is deposited in a fibrillar form which then may be incorporated into a granular form. Hair is formed by epithelial cells of a papilla at the base of the follicle. There is considerable variation in the rate of hair growth in meat animals. For example, the average length of bovine hair may reach a maximum between 6 and 24 months, and then may decrease.