Stratum Corneum

Also known as:  Corneal Layer;  Cornified Layer;  Horny Layer

The Stratum Corneum is the outermost of the four layers of the Epidermis of the Skin.  It consists of hard, tough, dead Cells whose Cytoplasm has been entirely replaced by Keratin - this layer is at its thickest on the soles of the feet and the palms of the hands.

Skin

 The Stratum Corneum is responsible for waterproofing the Skin (due to Keratin).

 The Stratum Corneum is involved in maintaining the Skin’s Water Balance:

 The Stratum Corneum can absorb Water that is present in the atmosphere or in cosmetic formulations (due to the Stratum Corneum’s content of Na-PCA).  The Stratum Corneum also prevents the absorption of excessive Water into the lower layers of the Skin.

 Water diffuses from the Dermis through the layers of the Epidermis and then evaporates when it arrives at the Stratum Corneum surface.  The quantity of Water that evaporates from the Stratum Corneum is governed largely by the relative humidity of the atmosphere (not by the endogenous Water content of the Skin).

 The Stratum Corneum functions as a flexible, renewable barrier between the external environment and the tissues and cells of the body.

Carbohydrates

 Hyaluronic Acid (applied topically or consumed orally) maintains a moisturizing film on the Stratum Corneum that may prevent the evaporation of Water from the Stratum Corneum: