Squamous epithelium

Squamous epithelium

In anatomy, squamous epithelium (from Latin "squama", "scale") is an epithelium characterised by its most superficial layer consisting of flat, scale-like cells called squamous cell. Epithelium may possess only one layer of these cells, in which case it is referred to as "simple squamous epithelium"; or it may possess multiple layers, referred to then as "stratified squamous epithelium". Both types perform differing functions, ranging from nutrient exchange to protection.

imple squamous epithelia

A simple squamous epithelium is a single layer of flat squamous cells that are all in contact with the basement membrane. The cells are irregularly shaped and very flat, so flat that the cell nucleus sometimes creates a bump in the surface of the cell. Gases and other substances can easily diffuse across squamous cells to the underlying basement membrane, and, because of their smooth surface, liquids can quickly flow over them. As such, simple squamous epithelia are seen lining body cavities and capillaries to reduce friction, as well as lining the alveoli of the lung to facilitate gas exchange.

tratified squamous epithelia

A stratified squamous epithelium consists of squamous (flattened) epithelial cells arranged in layers upon a basement membrane. Only one layer is in contact with the basement membrane; the other layers adhere to one another to maintain structural integrity. Although this epithelium is referred to as squamous, many cells within the layers may not be flattened; this is due to the convention of naming epithelia according to the cell type at the end.

This type of epithelium is well suited to areas in the body subject to constant abrasion, as the layers can be sequentially sloughed off and replaced before the basement membrane is exposed.

Stratified squamous epithelium is further classified by the presence or absence of keratin at the apical surface. Non-keratinised surfaces must be kept moist by bodily secretions to prevent them drying out and dying, whereas keratinised surfaces are kept hydrated and protected by keratin.

* Non-keratinizing stratified squamous epithelium (SSNKE): cornea (see also corneal epithelium), oral cavity, esophagus, rectum, vagina, and the internal portion of the lips
* Keratinizing stratified squamous epithelium (SSKE): skin, tongue (partially keratinised), and the external portion of the lips

function: protects underlying tissues in areas subjected to abrasionLocation: nonkeratinized type forms the moist linings of the esophagus, mouth, and vagina;keratinzed variety forms the epidermis of the skin, a dry membrane,rectum,epithelal is named by the shape of the apical surface

External links

*KansasHistology|epithel|epith02 Simple squamous epithelium of the glomerulus (kidney)
* [http://www.lima.ohio-state.edu/academics/biology/images/anatomy/Simple%20Squamous%20Epithelium%20400X.jpgDiagrams of simple squamous epithelium]
*KansasHistology|epithel|epith12 Stratified squamous epithelium of the vagina
*KansasHistology|epithel|epith14 Stratified squamous epithelium of the skin (thin skin)
*KansasHistology|epithel|epith15 Stratified squamous epithelium of the skin (thick skin)
* [http://bioweb.uwlax.edu/zoolab/Table_of_Contents/Lab-1b/Cross_section_of_the_esophagou/Stratified_squamous_epithelium/stratified_squamous_epithelium.htm Stratified squamous epithelium of the esophagus]


Wikimedia Foundation. 2010.

Игры ⚽ Нужно решить контрольную?

Look at other dictionaries:

  • squamous epithelium — see epithelium * * * epithelium composed of squamous cells; it may be either simple or stratified …   Medical dictionary

  • squamous epithelium — An epithelium in which the cells are flattened. May be a simple epithelium (eg. endothelium) or a stratified epithelium (eg. epidermis) …   Dictionary of molecular biology

  • squamous epithelium — noun : stratified epithelium that consists at least in its outer layers of small scalelike cells (as the epidermis of the human skin) compare columnar epithelium * * * Biol. epithelium consisting of one or more layers of scalelike cells …   Useful english dictionary

  • squamous epithelium — Biol. epithelium consisting of one or more layers of scalelike cells. * * * …   Universalium

  • squamous epithelium — see epithelium …   The new mediacal dictionary

  • simple squamous epithelium — squamous epithelium that has only one layer, such as in endothelium, mesothelium, and pulmonary alveoli. Called also pavement or tessellated e …   Medical dictionary

  • squamous epithelium — thin tissue layer that consists of scaly flat cells …   English contemporary dictionary

  • stratified squamous epithelium — epithelium such as that of typical skin, having a basal layer of cuboidal cells and overlying layers of squamous cells …   Medical dictionary

  • Squamous epithelial cell — Squamous epithelium is one of several types of epithelia. Code TH H2.00.02.0.01027 In …   Wikipedia

  • squamous carcinoma — n SQUAMOUS CELL CARCINOMA * * * squamous cell carcinoma 1. carcinoma developed from squamous epithelium, having cuboid cells and characterized by keratinization and often by preservation of intercellular bridges. In the skin, it may originate in… …   Medical dictionary

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”