[1] They contain a highly insoluble cornified envelope within the plasma membrane, and lipids (fatty acids, sterols and ceramides) released from lamellar bodies within the epidermis.
[4] Corneocytes, also referred to as squames (from Latin squama, meaning a "thin flake" or "scales") are terminally differentiated, anucleated cells of keratinocyte lineage that constitute the majority of stratum corneum, the outermost layer of the epidermis.
[5][6] Major constituents of corneocytes are keratin intermediate filaments organized in parallel bundles to form a matrix to give rigidity to the overall structure of the skin.
[7] Layers of corneocytes produce high mechanical strength which allows epidermis of the skin to perform its function as a physical, chemical and immunological barrier.
The components of the natural moisturizing factor absorb water from the atmosphere to ensure that the superficial layers of the stratum corneum stay hydrated.
[15] These include: Lamellar bodies are tubular or ovoid-shaped secretory organelles derived from the Golgi apparatus of keratinocytes in the upper part of stratum spinosum.
This perturbation induces lamellar bodies to undergo exocytosis and secrete lipids such as glycosylceramides, cholesterol and phospholipids to retrieve the permeability barrier function of stratum corneum.
[8][18] These hydrophobic components fuse together to form multiple bilayers of lipids between corneocytes to act as the principal barrier to the transcutaneous movement of water and electrolytes.
As a result of the weakened corneodesmosomes in the outer skin surface, the uppermost layers of corneocytes get exfoliated through frictional forces such as rubbing or washing.
[9] Dry skin (xerosis) involves increased thickness of stratum corneum (hyperkeratosis), which may occur due to various reasons including aging, humidity of the environment or UV irradiation.