Stratum Corneum
Pronunciation: STRA-tum KOR-nee-um
The outermost layer of the epidermis, composed of dead, flattened, keratin-filled corneocytes, forming the primary physical and chemical barrier of the skin.
Full Definition
The stratum corneum is the terminal differentiation product of the epidermis, consisting of approximately 15–20 layers of anucleate, keratin-rich corneocytes embedded in a lipid matrix of ceramides, cholesterol, and fatty acids. It serves as the principal barrier against transepidermal water loss (TEWL), environmental pathogens, and chemical penetration. Disruption of the stratum corneum is central to the pathophysiology of atopic dermatitis, ichthyosis, and contact dermatitis. Editors should italicise 'stratum corneum' only when following a style guide that italicises anatomical Latin terms; many modern clinical style guides do not require italicisation of anatomical layer names.
Usage
Usage note: Italicisation varies by house style; verify whether the publication italicises anatomical Latin terms. Do not confuse with deeper epidermal layers (stratum granulosum, stratum spinosum, stratum basale), which have distinct functions.
In Context
- "Transepidermal water loss measurements reflect the integrity of the stratum corneum barrier function." — Biophysical methods section
- "The author inconsistently italicised 'stratum corneum' in some sections but not others; the editor standardized according to house style." — Copy-editing note