Information about Epidermis (skin)
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Cross-section of all skin layers
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Optical Coherence Tomography tomogram of fingertip, depicting stratum corneum (~500µm thick) with stratum disjunctum on top and stratum lucidum (connection to stratum spinosum) in the middle. At the bottom superficial parts of the dermis. Sweatducts are clearly visible.
Components
The epidermis contains no blood vessels, and is nourished by diffusion from the dermis. The main type of cells which make up the epidermis are keratinocytes, melanocytes, Langerhans cells and Merkels cells.Layers
The epidermis is divided into several layers where cells are formed through mitosis at the innermost layers. They move up the changing shape and composition as they differentiate and become filled with keratin. They eventually reach the top layer called stratum corneum and become sloughed off, or desquamated. This process is called keratinization and takes place within weeks. The outermost layer of epidermis consists of 25 to 30 layers of dead cells.Sublayers
Epidermis is divided into the following 5 sublayers or strata, listed from the superficial to deep:- Stratum corneum
- Stratum lucidum
- Stratum granulosum
- Stratum spinosum
- Stratum germinativum (also called "stratum basale")
- "Corn Lovers Grow Several Bales" (from superficial to deep)
- "Before Signing, Get Legal Counsel" (from deep to superficial)
Additional images
) Section of epidermis. | ) Skin layers. | _Dyshidrotic_.JPG')) Histopathological image of dyshidrotic dermatitis, showing focal spngiotic change in the epidermis. | ) Schematics of external human skin depicting its inner structure. |
) The distribution of the bloodvessels in the skin of the sole of the foot. | ) Cross section showing layers of epidermis. |
External links
- Histology at BU 08422loa - "Integument: thick skin"
Integumentary system | |
|---|---|
| structures | Skin • Sweat glands • Sebaceous glands • Hair (Hair follicle) • Nails • Scale |
| layers | Epidermis (Stratum corneum, Stratum lucidum, Stratum granulosum, Stratum spinosum, Stratum germinativum/basale) • Dermis • Subcutis |
Skin layers: epidermis, dermis, and subcutis, showing a hair follicle, sweat gland & sebaceous gland.]] In zootomy and dermatology, skin is the largest organ of the integumentary system made up of multiple layers of epithelial tissues that guard underlying muscles and organs.
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epithelium is a tissue composed of a layer of cells. Epithelium lines both the outside (skin) and the inside cavities and lumen of bodies. The outermost layer of our skin is composed of dead stratified squamous, keratinized epithelial cells.
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basal lamina is a layer on which epithelium sits and which is secreted by the epithelial cells. It is often confused with the basement membrane, and sometimes used inconsistently in the literature, see below.
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The blood vessels are part of the cardiovascular system and function to transport blood throughout the body. The most important types, arteries and veins, carry blood away from or towards the heart, respectively.
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- This article is about the physical mechanism of diffusion. For alternative meanings, see diffusion (disambiguation).
Diffusion is the net movement of particles from an area of high concentration to an area of low concentration.
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The dermis is a layer of skin beneath the epidermis that consists of connective tissue and cushions the body from stress and strain. The dermis is tightly connected to the epidermis by a basement membrane. It also harbors many nerve endings that provide the sense of touch and heat.
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The keratinocyte is the major cell type of the epidermis, making up about 90% of epidermal cells. The epidermis is divided into four or five layers (depending on the type of skin) based on keratinocyte morphology:
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- stratum basale (at the junction with the dermis)
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Melanocytes are cells located in the bottom layer (the stratum basale) of the skin's epidermis and in the middle layer of the eye (the uvea).
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Melanogenesis
Through a process called melanogenesis..... Click the link for more information.
Langerhans' cells are dendritic cells abundant in epidermis, containing large granules called Birbeck granules and can be found in other organs in the condition Histiocytosis.
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Merkel cells are large oval cells found in the skin of vertebrates. They are associated with the sense of touch, and are responsible for the highly malignant skin tumor known as Merkel cell carcinoma.
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Keratins are a family of fibrous structural proteins; tough and insoluble, they form the hard but nonmineralized structures found in reptiles, birds, amphibians and mammals. They are rivaled as biological materials in toughness only by chitin.
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The stratum corneum ("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 (basale).
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stratum lucidum (Latin for "clear layer") is a thin, clear layer of dead skin cells in the epidermis, and is named for its translucent appearance under a microscope. It contains a clear substance called eleidin, which eventually becomes keratin.
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In microscopic views of skin, the stratum granulosum layer of the epidermis lies between the stratum spinosum below and the stratum lucidum above in stratified squamous keratinized thick skin of palms and soles.
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In the skin, the stratum spinosum is a multi-layered arrangement of cuboidal cells that sits beneath the stratum granulosum. Adjacent cells are joined by desmosomes, giving them a spiny appearance when the cells shrink during the staining process while the desmosomes hold firm.
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Stratum germinativum (also stratum basale or basal cell layer) is the layer of keratinocytes that lies at the base of the epidermis immediately above the dermis.
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Not to be confused with pneumonic.
A mnemonic (pronounced IPA: /niːˈmɒnɪk/ in RP, /nɨˈmɑnɨk/
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Boston University (BU) is a private research university located in Boston, Massachusetts, United States. Although chartered by the Massachusetts Legislature in 1869, Boston University traces its roots to the establishment of the Newbury Biblical Institute in Newbury,
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In zootomy, the integumentary system is the external covering of the body, comprising the skin, hair, feathers, scales, nails, sweat glands and their products (sweat and mucus).
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Skin layers: epidermis, dermis, and subcutis, showing a hair follicle, sweat gland & sebaceous gland.]] In zootomy and dermatology, skin is the largest organ of the integumentary system made up of multiple layers of epithelial tissues that guard underlying muscles and organs.
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Perspiration (also called sweating or sometimes transpiration) is the production and evaporation of a fluid, consisting primarily of water as well as a smaller amount of sodium chloride (the main constituent of "table salt"), that is excreted by the sweat glands in the skin of
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The sebaceous glands are glands found in the skin of mammals.
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Locations and morphology
A branched type of acinar gland, these glands exist in humans throughout the skin except in the palms of the hands and soles of the feet...... Click the link for more information.
Hair is a filamentous outgrowth of protein, found only on mammals. It projects from the epidermis, though it grows from hair follicles deep in the dermis. Although many other organisms, especially insects, show filamentous outgrowths, these are not considered "hair".
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A hair follicle is part of the skin that grows hair by packing old cells together. Attached to the follicle is a sebaceous gland, a tiny sebum-producing gland found everywhere except on the palms, lips and soles of the feet.
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nail is a horn-like structure at the end of a human's or an animal's finger or toe. See also claw.
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Parts of the nail
Anatomically fingernails and toenails..... Click the link for more information.
scale (Greek lepid, Latin squama) is a small rigid plate that grows out of an animal's skin to provide protection. In lepidopteran species, scales are plates on the surface of the insect wing, and provide coloration.
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The stratum corneum ("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 (basale).
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stratum lucidum (Latin for "clear layer") is a thin, clear layer of dead skin cells in the epidermis, and is named for its translucent appearance under a microscope. It contains a clear substance called eleidin, which eventually becomes keratin.
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In microscopic views of skin, the stratum granulosum layer of the epidermis lies between the stratum spinosum below and the stratum lucidum above in stratified squamous keratinized thick skin of palms and soles.
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