The stratum corneum is the outermost layer of theepidermis.
It also helps to keep moisture from evaporating into the atmosphere, which keeps the skin hydrated.
The stratum corneum was thought to be basically inert, or inactive.
Youngoldman / Getty Images
Corneocytes
The stratum corneum often is described as having a brick-and-mortar jot down of structure.
As the name suggests, keratocytes primarily consist of keratin.
It’s at this point that they’re considered corneocytes.
Lamellar Bodies
Lamellar bodies are organelles that form within keratinocytes.
This triggers the release ofthree types of lipidsfree fatty acids, cholesterol, and ceramides.
Cell Envelope
Each corneocyte is surrounded by a shell called a cornified cell envelope.
Of these proteins, loricrin makes up more than 70% of the cell envelope.
Corneodesmosomes
Holding the corneocytes together are specialized protein structures called corneodesmosomes.
These structures also are part of the “mortar” in the brick-and-mortar analogy.
Corneodesmosomes are the structures that must be degraded for the skin to be shed.
These compounds comprise approximately 20%30% of the weight of the corneocyte.
The lipid layer surrounding the corneocyte helps seal the corneocyte to prevent the loss of NMF.
For this process to take place, certain enzymes cause the destruction of the corneodesmosomes.
How these enzymes are activated isn’t fully understood.
Sun exposure can also cause damage to the stratum corneum.
Murphrey MB.Histology, Stratum Corneum.StatPearls [Internet].
doi:10.1002/adma.201606596
Feingold KR.Lamellar bodies: the key to cutaneous barrier function.J Invest Dermatol.
2012;132(8):1951-3. doi:10.1038/jid.2012.177.
Effects of lipid extraction and soaking.International Journal of Cosmetic Science.
2010;32(5):394-394. doi:10.1111/j.1468-2494.2010.00591_2.x
Pappas A.Epidermal surface lipids.Dermatoendocrinol.
