Stratum germinativum (also stratum basale or basal cell layer) is the layer of keratinocytes that lies at the base of the epidermis immediately above the dermis. It consists of a single layer of tall, simple columnar epithelial cells lying on a basement membrane. These cells undergo rapid cell division, mitosis to replenish the regular loss of skin by shedding from the surface. About 25% of the cells are melanocytes, which produce melanin which provides pigmentation for skin and hair.
All melanocytes have the capacity to migrate widely in the embryo, and therefore a cancer of a melanocyte, a melanoma, will spread (metastasize) very easily. For this reason, melanomas are often fatal, and when surgically removed, a lot of surrounding tissue must be taken as well.
Albinism is a recessive hereditary condition in which the melanocytes do not produce melanin. People appear very pale and, depending on the type of albinism, will also have lack of pigment in the iris of the eye causing them to appear pink or violet due to visability of the underlying blood vessels. In the most commonly inherited form of albinism the eyes are blue.
Cross-section of all skin layers.
- Information on Basal Cell Carcinoma from The Skin Cancer Foundation
- Histology image: 08422loa – Histology Learning System at Boston University - "Integument: thick skin"