Stratum corneum

Common card · No. 285152

The stratum corneum (Latin for 'horned/horny layer') is the outermost layer of the epidermis of the tetrapod skin. In human skin, it consists of a stratified squamous epithelium made of 15 to 20 layers of corneocytes, flattened, terminally differentiated keratinocytes that have lost their nuclei or organelles. The filamentous keratin within the cytoplasm of these cells forms a semi-impermeable cuticle that protects underlying tissues from external insults such as dehydration, infection, direct chemical exposure and mechanical abrasion. Hyperkeratosis and hyperplasia of the stratum corneum, often in response to excessive abrasions or impacts, can lead to the formation of hardened skin conditions such as calluses, corns and hangnails. Among the properties of the stratum corneum are mechanical shear, impact resistance, water flux and hydration regulation, microbial proliferation and invasion regulation, initiation of inflammation through cytokine activation and dendritic cell activity, and...

Read on Wikipedia · Image Mikael Häggström, based on work by Wbensmith, CC BY-SA 3.0