Skin. Coloured scanning electron micrograph of a section through human skin. The uppermost skin layer is the epidermis (orange & yellow). The stratum corneum (top, orange) is a cornified layer composed of flattened, fused keratin-rich cell remnants which forms the surface of the epidermis. The dead cells from this layer are continuously being shed and replaced from cells from the living epidermal layers below (yellow). These layers contain keratinocytes, specialized cells that synthesize keratin. The lowest layer shown here is the dermis (pink). The dermis is a thick layer of fibrous connective tissue which supports and nourishes the epidermis. Magnification unknown.