Stratum basale

The stratum basale consists of a single layer of cuboidal to columnar shaped cells and rests on the basement membrane of the epidermis.  These cells accumulate melanin granules, which are synthesized by neighboring melanocytes.  The majority of keratinocyte proliferation occurs in stratum basale.

Melanocytes are located primarily in the stratum basale, although they can also be found in the stratum spinosum.  Melanocytes synthesize melanin pigment, which they package into melanosomes (melanin granules) that are transferred to neighboring keratinocytes.  Melanin protects nuclear DNA in keratinocytes against ultraviolet light.

Melanocytes are located primarily in the stratum basale, although they can also be found in the stratum spinosum.  Melanocytes synthesize melanin pigment, which they package into melanosomes (melanin granules) that are transferred to neighboring keratinocytes.  Melanin protects nuclear DNA in keratinocytes against ultraviolet light.

Stratum spinosum, the layer immediately above stratum basale, consists of 3-10 layers of cells and is the major site of keratin filament synthesis in the epidermis.  Cells of the stratum spinosum are securely bound to each other by desmosomes, which aid the epidermis in resisting frictional trauma and account for the spiny appearance of these cells.