Epidermal stratum corneum and keratinocyte layer

The skin stratum corneum and keratinocyte layer represent the primary physical and chemical barrier of the human body, serving as the first line of defense against environmental stressors (StatPearls, 2023). The stratum corneum, the outermost epidermal layer, consists of protein-rich corneocytes embedded in a specialized lipid matrix, creating a brick and mortar structure that prevents transepidermal water loss (PubMed, PMID: 24656726). Beneath this, the keratinocyte layers (granulosum, spinosum, and basale) contain cells that undergo a programmed differentiation process known as cornification (NIH, 2022). This tissue is not a single molecular target but rather a complex anatomical structure that is the primary site for topical drug delivery and the focus of treatments for various dermatoses (Journal of Investigative Dermatology, 2012). In conditions such as psoriasis and atopic dermatitis, the integrity and function of these layers are compromised, leading to impaired barrier properties and chronic inflammation (PubMed, PMID: 30130617). Therapeutic interventions often aim to restore the barrier, promote healthy desquamation, or modulate the underlying cellular activity to treat skin disease.

Other names

EpidermisStratum corneumHorny layerKeratinized layerSkin barrier

Topical agents interact with these layers by promoting desquamation (keratolytics), replenishing intercellular lipids (emollients), or modulating keratinocyte proliferation and differentiation (retinoids).