Stratum corneum

The outermost epidermal layer, formed by flattened dead cells embedded in a lipid-rich matrix. It limits water loss and helps block chemicals and microbes.

Corneocyte: A flattened, enucleated cell that forms the structural units of the stratum corneum. Corneocytes form the cellular part of its barrier.
Epidermis: The outer epithelial layer of skin, organized into strata and continually renewed. The stratum corneum is the epidermis's outermost layer.
Transepidermal water loss: The passive movement of water through the epidermis and its evaporation from the skin surface. It is a measurable indicator of how well this layer restricts water loss.
Stratum lucidum: A thin, translucent epidermal layer found between the stratum corneum and granular layer in thick skin. It lies beneath the stratum corneum and appears only in thick skin.
Skin barrier: The body's protective interface that limits water loss and exposure to external agents. The stratum corneum is the skin barrier's outermost and principal component.
Keratinocyte: The predominant cell type of the epidermis, which produces keratin and matures toward the skin surface. Keratinocytes differentiate into the corneocytes that populate this layer.
Percutaneous absorption: The passage of substances through the skin, including across the epidermal barrier. The stratum corneum is usually the main resistance to substances entering through skin.
Stratum granulosum: The epidermal layer beneath the stratum corneum, containing keratinocytes with prominent granules. Unlike the dead cells above it, this layer contains living keratinocytes completing differentiation.
Ceramide: A family of lipid molecules found in cell membranes and especially abundant in the stratum corneum. Ceramides help form the lipid matrix between corneocytes.
Keratin: A family of tough structural proteins found in epithelial cells, including corneocytes. Keratin filaments strengthen corneocytes and help them resist mechanical stress.

Linked from 27 pages