The stratum corneum is the outer layer of the epidermis. It is composed of flat, dead cells which have lost their nuclei. It is constantly being sloughed off as dandruff. These cells are rubbed off as you move, wear clothes, and wash. Keratin, a horny protein found in hair and fingernails, is also found in the cells of the stratum corneum and prevents evaporation. It also helps to ward off injury because of its toughness.
