This scanning micrograph shows an empty hair follicle and surrounding skin, magnified 600 times. Except for the palms of the hands and soles of the feet, all areas of the human skin contain such tube-like follicles, from which hairs grow. Individual hairs last for up to seven years before being shed and replaced by a new hair growing from the same follicle. Just below the surface of the follicle is the sebaceous gland, which produces sebum, an oily substance that keeps the hair and skin supple.