What is stratum corneum composed of?
In terrestrial vertebrates, the epidermis covering the body often forms an outer keratinized or cornified layer, the stratum corneum. This helps them survive especially in a drying and abrasive terrestrial environment. All cells in the stratum corrneum are dead cells. New epidermal cells are formed by mitotic division (in the deep stratum basale). These new epidermal cells push more superficial ones toward the surface, where they tend to self destruct in an orderly fashion. During their death, various protein products accumulate and form keratin in a process called keratinization. This serves to reduce water loss.