Flexi Says: Dogs grow fur in the same way that people grow hair. In fact, all mammal fur and hair is similar in structure and evolved from the same common ancestor. The main component of fur and hair is the tough protein keratin. Hair grows from follicles deep in the dermis, the lower layer of skin. A follicle is shaped like a tube that goes from the dermis to the surface of the skin. Hair grows from the bottom of the follicle. Cells at the root of the hair rapidly divide. As more cells are added, the older cells are pushed upward. The cells make a coating of keratin protein. The cells die as the hair grows longer, and only the protein coating remains.
