Hair. Light micrograph of a cross-section through hairs of the human skin. Two circular hair shafts are seen (purple) embedded in the dermis (white) of the skin. Epidermis (blue) surrounds each hair as an ingrowth of the skin surface. Hair consists of an outer cuticle layer of cells; the bulk of the hair consists of cortex (stained purple) that contains the pigment which gives hair its colour; and a central core or medulla (pink) that as here may be hollow. Hair is made of the fibrous protein keratin. Most hair cells are dead except for a growing bulb region at the base of the hair shaft. Magnification: x50 at 35mm size.