surface, it is called fur. In humans, some hair is found every- where in the skin except the palms, soles, lips, nipples, parts of the genitalia, and the distal segments of the fingers and toes. The shaft of the hair protrudes above the surface of the skin, whereas the root and hair bulb are below the surface(figure 5.5a). A hair has a hard cortex(bark), which sur- rounds a softer center, the medulla(me-dool'a). The cortex is covered by the cuticle(ku'ti-kl, kin), a single layer of overlapping cells that holds the hair in the hair follicle. The hair follicle is an extension of the epidermis deep into the dermis, and it can play an important role in tissue repair. If the surface epidermis is damaged, the epithelial cells within the hair follicle can divide and serve as a source of new ep ithelial cells.