Global Dermatology » The Basal Layer (Stratum Basale of the Epidermis)

This is the deepest layer of the epidermis.
It lies just above the basement membrane to which it is linked with proteins called hemidesmosomes.
These are partially differentiated skin cells which will progressively turn into the dead, nucleus-free, har keratinocytes of the stratum corneum (corneocytes).
- Basal Epidermal keratinocytes have in their cytoplasm (cell ‘s”empty area”) many bundles of keratin intermediate filaments, as well as actin and microtubule networks, which mediate changes to flatten as the cells travel upwards until the cell reaches the upper layers.
They are regular in shape and appear as regular cubes to rectangles under the microscope. Some basal keratinocytes lying close to the dermal papillae are stem cells – naturally located close to richly vascularized structures.
- Stem cells can divide into daughter cells, one which will differentiate and the other which will remain as another
- Stem cells divide almost indefinitely.
Also present in the Basal Layer are pigment cells called melanocytes, there is roughly one of them for every 10 cells. Other cells include Merkel cells, which are involved in light touch.
Basal Cell Carcinomas (BCC) are thought to derive from Basal Cells, although the cells of origin are thought to be located in a specific area of the hair follicle called the infundibulum.

The Basal Layer (Stratum Basale of the Epidermis)