THE LAYERS OF THE EPIDERMIS OF THE SKIN

The epidermis of the skin refers to the topmost layer. It is composed of five layers. From the surface to the deep layers, the names are:

1. Stratum corneum
2. Stratum lucidum
3. Stratum granulosum
4. Stratum spinosum
5. Stratum basale or germinativum

STRATUM CORNEUM
This layer consists of dead cells with a hard protein envelope. These cells contain keratin surrounded by lipid. It is a tough water resistant layer. They are flat, anucleated  and cornified cells.

STRATUM LUCIDUM
This layer consists of dead cells containing dispersed keratohyalin granules. This layer is found in thick thick skins only such as the palm and soles.

STRATUM GRANULOSUM
This layer consists of cells that contain keratohyalin granules and lamellar bodies that have released lipids. They, therefore, look granular. The cells are covered by hard protein. They are polygonal cells with basophylic granules.

STRATUM SPINOSUM
This layer consists of cells that are accumulating keratin fibers and lamellar bodies. The are cuboidal like cells and desmosomes in between.

STRATUM BASALE
The cells in this layer undergo mitosis (cell division) to reproduce the top layers. The are columnar- like cells. The keratinocytes arise from this layer.They produce keratin. Keratin makes our skin tough. It provides protection from microorganisms, physical harm, and chemical irritation.  


Here is a diagram illustrating the layers.