The stratum corneum ("the horny layer") is the outermost layer of the epidermis (the outermost layer of the skin). It is composed mainly of dead cells that lack nuclei. As these dead cells slough off, they are continuously replaced by new cells from the stratum germinativum. In the human forearm, for example, about 1300 cells/cm²/hr are shed and commonly accumulate as house dust. Image File history File links Skinlayers. ... Latin is an ancient Indo-European language originally spoken in Latium, the region immediately surrounding Rome. ... Elseviers logo. ... It has been suggested that this article or section be merged with skin. ... It has been suggested that this article or section be merged with Epidermis (skin). ... Drawing of the structure of cork as it appeared under the microscope to Robert Hooke from Micrographia which is the origin of the word cell. Cells in culture, stained for keratin (red) and DNA (green). ... The eukaryotic cell nucleus. ... Stratum germinativum or stratum basale is the layer of keratinocytes that lies at the base of the epidermis immediately above the dermis. ...

Cells of the stratum corneum contain keratin, a protein that helps keep the skin hydrated by preventing water evaporation. In addition, these cells can also absorb water, further aiding in hydration and explaining why humans and other animals experience wrinkling of the skin on the fingers and toes (colloquially called "pruning") when immersed in water for prolonged periods. Microscopy of keratin filaments inside cells. ... A representation of the 3D structure of myoglobin, showing coloured alpha helices. ... Impact of a drop of water Water is a chemical substance that is essential to all known forms of life[1]. It covers 71% of Earths surface. ... This article or section is in need of attention from an expert on the subject. ... Look up absorption in Wiktionary, the free dictionary. ... A wrinkled finger after a warm bath A wrinkle is a ridge or crease of a surface. ... Fingers of the human left hand A finger is a type of digit, an organ of manipulation and sensation found in the hands of humans and other primates. ... Toes are the digits of the foot of a human or animal. ...

The thickness of the stratum corneum varies according to the amount of protection and/or grip required by a region of the body. For example, the hands are typically used to grasp objects, requiring the palms to be covered with a thick stratum corneum. Similarly, the sole of the foot is prone to injury, and so it is protected with a thick stratum corneum layer. In general, the stratum corneum contains 15 to 20 layers of dead cells. For other uses, see Hand (disambiguation). ... Look up Sole in Wiktionary, the free dictionary. ... For other uses, see Foot (disambiguation). ...

In reptiles, the stratum corneum is permanent, and is only replaced during times of rapid growth, in a process called ecdysis or moulting. The stratum corneum in reptiles contains beta-keratin which provides much more rigid skin layer. Subclasses Anapsida Diapsida Synonyms Reptilia Laurenti, 1768 Reptiles are tetrapods and amniotes, animals whose embryos are surrounded by an amniotic membrane, and members of the class Sauropsida. ... Ecdysis is the molting of the cuticula in arthropods and related groups (Ecdysozoa). ... In birds, moulting or molting is the routine shedding of old feathers. ... ß-keratin or beta-keratin is an optical isomer of alpha-keratin. ...

Additional images

Cross-section of all skin layers. Image File history File linksMetadata Skin. ...

External links

• MedEd at Loyola medicine/dermatology/skinlsn/stcorn.htm
• Stratum corneum - WebMD anatomy
• Histology at BU 08422loa - "Integument: thick skin"