[noun] Dead cells or corneocytes make up the stratum corneum, the most superficial layer of the epidermis. The epidermis is made up of layered keratinocytes, which evolve and migrate toward the skin’s surface, turning into corneocytes.
Corneocytes are flattened, keratin-rich cells that form an effective protective barrier on the skin. Once they have accumulated on the surface, these dead cells detach from each other, falling away to create space for younger cells. This cellular-renewal process continues for 21 to 28 days, the time required for these cells to migrate to the skin’s surface.