The stratum basale is the deepest layer of the epidermis. It is only one cell thick and has a basement membrane upon which it is adhered, superficial to the dermis.
It contains dividing undifferentiated cells - up to a third of the population of cells here may be dividing at any one time - which repopulate the overlying layers in a cyclical manner to maintain a roughly constant epidermal thickness. Mitosis can take between 2-5 days. Once daughter cells ascend to the stratum spinosum, they differentiate into keratinocytes.
The cells of the stratum basale have numerous intracellular organelles indicating their rapid synthetic activity. Amongst products of the cell are tonofilaments which are involved in keratin production.
The stratum basale can be involved in a range of skkin disorders e.g. basal cell tumours and psoriasis.
Last reviewed 01/2018