epithelium
[ep″ĭ-the´le-um] (pl. epithe´lia) (Gr.)the cellular covering of internal and external surfaces of the body, including the lining of vessels and other small cavities. It consists of cells joined by small amounts of cementing substances. Epithelium is classified into types on the basis of the number of layers deep and the shape of the superficial cells.
ciliated epithelium epithelium bearing vibratile, hairlike processes (cilia) on its free surface.
columnar epithelium epithelium whose cells are of much greater height than width.
cuboidal epithelium epithelium whose cells are of approximately the same height and width, and appear square in transverse section.
germinal epithelium thickened peritoneal epithelium covering the gonad from earliest development; formerly thought to give rise to germ cells.
glandular epithelium that composed of secreting cells.
pigmentary epithelium (pigmented epithelium) that made of cells containing granules of pigment.
sense epithelium (sensory epithelium) neuroepithelium (def. 1).
simple epithelium that composed of a single layer of cells.
squamous epithelium that composed of flattened platelike cells.
stratified epithelium epithelium made up of cells arranged in layers.
transitional epithelium a type characteristically found lining hollow organs, such as the urinary bladder, that are subject to great mechanical change due to contraction and distention; originally thought to represent a transition between stratified squamous and columnar epithelium.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.
ep·i·the·li·um
, pl.ep·i·the·li·a
(ep'i-thē'lē-ŭm, -ă), [TA]The purely cellular avascular layer covering all free surfaces, cutaneous, mucous, and serous, including the glands and other structures derived therefrom.
[G. epi, upon, + thēlē, nipple, a term applied originally to the thin skin covering the nipples and the papillary layer of the border of the lips]
Farlex Partner Medical Dictionary © Farlex 2012
epithelium
(ĕp′ə-thē′lē-əm)n. pl. epithe·lia (-lē-ə) or epithe·liums
Membranous tissue composed of one or more layers of cells separated by very little intercellular substance and forming the covering of most internal and external surfaces of the body and its organs.
ep′i·the′li·al adj.
The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.
ep·i·the·li·um
, pl. epithelia (ep'i-thē'lē-ŭm, -ă) [TA]The purely cellular avascular layer covering all the free surfaces, cutaneous, mucous, and serous, including the glands and other structures derived therefrom.
[G. epi, upon, + thēlē, nipple, a term applied originally to the thin skin covering the nipples and the papillary layer of the border of the lips]
Medical Dictionary for the Health Professions and Nursing © Farlex 2012
epithelium
The non-stick coating cell layer for all surfaces of the body except the insides of blood and lymph vessels. Epithelium may be single-layered, or ‘stratified’ and in several layers, with the cells becoming flatter and more scaly towards the surface, as in the skin. It may be covered with fine wafting hair-like structures (cilia), as in the respiratory tract, and it may contain mucus-secreting ‘goblet’ cells. See also ENDOTHELIUM and EPIDERMIS.Collins Dictionary of Medicine © Robert M. Youngson 2004, 2005
)
Fig. 153 Epithelium (1) . Types of epithelium.
epithelium
- (in animals) a layer of covering cells lying on a basement membrane that is called simple epithelium when one cell thick and compound epithelium when several cells thick, and usually covers connective tissue embryologically derived from the ECTODERM. The cells sometimes have a secretory function and are held together by a cementing substance to form a sheet. Their shape gives rise to names descriptive of the cells, e.g. columnar, cubical, squamous (see Fig. 153 ). Where the epithelium is more than one cell thick it is described as stratified. Similar cells can be derived from MESODERM and are referred to as mesothelium when lining the COELOM, and as ENDOTHELIUM when lining blood vessels.
- (in plants) a layer of cells lining cavities and secretory canals, for example, resin canals.
Collins Dictionary of Biology, 3rd ed. © W. G. Hale, V. A. Saunders, J. P. Margham 2005
Epithelium
Cells composing the lining of an organ.
Mentioned in: Colon Cancer, Rectal Cancer
Gale Encyclopedia of Medicine. Copyright 2008 The Gale Group, Inc. All rights reserved.
ep·i·the·li·um
, pl. epithelia (ep'i-thē'lē-ŭm, -ă) [TA]The purely cellular avascular layer covering all free surfaces, cutaneous, mucous, and serous, including the glands and other structures derived therefrom.
[G. epi, upon, + thēlē, nipple, a term applied originally to the thin skin covering the nipples and the papillary layer of the border of the lips]
Medical Dictionary for the Dental Professions © Farlex 2012