Histology, Stratum Corneum

In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan.


As the outermost layer of the epidermis, the stratum corneum is the first line of defense for the body, serving an essential role as a protective skin barrier against the external environment. The stratum corneum aids in hydration and water retention, which prevents cracking of the skin, and is made up of corneocytes, which are anucleated keratinocytes that have reached the final stage of keratinocyte differentiation. Corneocytes retain keratin filaments within a filaggrin matrix, and the cornified lipid envelope replaces the keratinocyte plasma membrane. These flat cells organize in a brick-and-mortar formation within a lipid-rich extracellular matrix. Pathophysiology of the stratum corneum is typically secondary to either protein or lipid defects (see Illustration. Illustration of Cells of the Epidermis). Other clinically significant signs include parakeratosis, which is the incomplete maturation of keratinocytes, and the morphological retention of nuclei in the stratum corneum. Abnormal parakeratosis of the stratum corneum can appear in patients with psoriasis, chronic eczema, and squamous cell carcinoma. Scaling, or visible peeling and flaking of the skin, furthermore is a salient manifestation of diseases of the stratum corneum.

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