- The outermost layer of the epidermis, called the stratum corneum, is composed of dead skin cells that have shed the nuclei they carry and have flattened, hardened, lost flexibility, and become scale-like.
- In contrast, the deeper layers of the epidermis, consisting of the deeper-lying stratum spinosum and the basal layer (stratum basale), consist of viable, actively metabolizing epidermal cells.