The Stratum Corneum
The Stratum Corneum — the outermost sublayer of the epidermis, made of flattened, dead keratinocytes embedded in a lipid matrix that together form the skin's main barrier. It limits water loss and blocks entry of irritants, allergens, and microbes. Its integrity is central to hydration and overall skin health.
Key points
- The stratum corneum is the top layer of the epidermis, often compared to a brick-and-mortar structure of cells and lipids.
- Its corneocytes are flattened, non-living keratinocytes surrounded by lipids such as ceramides, cholesterol, and fatty acids.
- It is the primary barrier limiting transepidermal water loss and protecting against environmental aggressors.
- A compromised stratum corneum can lead to dryness, sensitivity, and increased susceptibility to irritation.
Frequently asked
Is the stratum corneum made of living cells?
No, it consists mainly of corneocytes, which are flattened dead keratinocytes that have lost their nuclei, held together by intercellular lipids.
Why is the stratum corneum important in skincare?
It forms the skin's outer barrier that retains moisture and blocks irritants, so supporting it with lipids and humectants helps maintain hydration and resilience.
Related topics
This is a foundational entry in the SYNC Skin Encyclopedia and is expanded over time. Educational information only — not medical advice.
