The deepest layer of the epidermis is called the Stratum Basale. Keratinocytes, which are new epidermal cells, are formed here via cell division in order to replace the cells that are constantly being shed in the outer layers of the epidermis. As the older cells are pushed upwards, they harden through the process of keratinization and accumulate to form the outer layer of the epidermis.
Cellular components
The epidermis primarily consists of keratinocytes[4] (proliferating basal and differentiated suprabasal), which comprise 90% of its cells, but also contains melanocytes, Langerhans cells, Merkel cells,[6]:2–3 and inflammatory cells. Epidermal thickenings called Rete ridges (or rete pegs) extend downward between dermal papillae.[7]Blood capillaries are found beneath the epidermis, and are linked to an arteriole and a venule. The epidermis itself has no blood supply and is nourished almost exclusively by diffused oxygen from the surrounding air.[8]