from The American Heritage® Dictionary of the English Language, 4th Edition

  • n. 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.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • n. A membranous tissue composed of one or more layers of cells which forms the covering of most internal and external surfaces of the body and its organs: internally including the lining of vessels and other small cavities, and externally being the skin.

from the GNU version of the Collaborative International Dictionary of English

  • n. The superficial layer of cells lining the alimentary canal and all its appendages, all glands and their ducts, blood vessels and lymphatics, serous cavities, etc. It often includes the epidermis (i. e., keratin-producing epithelial cells), and it is sometimes restricted to the alimentary canal, the glands and their appendages, -- the term endothelium being applied to the lining membrane of the blood vessels, lymphatics, and serous cavities.

from The Century Dictionary and Cyclopedia

  • n. In anatomy, the superficial layer of cells of mucous membranes, covering the connective-tissue layer, corresponding to the epidermis of the outer skin and continuous with it at the mouth and other natural openings.
  • n. In ornithology, specifically, the dense, tough cuticular lining of the gizzard. It is sometimes even bony, and sometimes deciduous.
  • n. In botany, a delicate layer of cells lining the internal cavities of certain organs, as the young ovary, etc.: also applied to the thin epidermis of petals.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • n. membranous tissue covering internal organs and other internal surfaces of the body


from The American Heritage® Dictionary of the English Language, 4th Edition

New Latin epithēlium : epi- + Greek thēlē, nipple; see dhē(i)- in Indo-European roots.

from Wiktionary, Creative Commons Attribution/Share-Alike License

Modern Latin epithēlium, from Ancient Greek ἐπί (epi, "on, atop, epi-") + θηλή (thēlē, "nipple").


  • Vitamin A promotes a healthy intestinal epithelium, which is important for optimal absorption of nutrients, and it also promotes strong joints.

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  • People with IBS experience some dysfunction of the immune and nervous systems that regulate the lining of the bowel; this lining called the epithelium is what regulates the flow of fluids into and out of the intestines.

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  • It was thought that macrophage cells with TLRs didn't sense beneficial or neutral bacteria in part because such bacteria were protected by the lining of the gut and other organs, called the epithelium, which was believed to keep macrophage cells on one side and bacteria on the other.

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  • Such a transverse section of a chick embryo, at the end of the first day of incubation, shows the gut-gland layer as a very simple epithelium, which is spread like a leaf over the outer surface of the food-yelk (Figure 1.92).

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  • Mutant forms of RPE65 prevent the production of this enzyme in a "nursery" layer of cells called the retinal pigment epithelium, which is attached to the retina and nourishes photoreceptors by breaking down retinol, among other cellular services.

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  • An unwanted complication of erosive esophagitis is Barrett's epithelium, which is the pre-malignant condition for adenocarcinoma of the esophagus.

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  • The epithelium is a layer of cells forming the epidermis of the skin and the surface layer of mucous and serous membranes.

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  • "Eighty-five percent of cancers originate from the epithelium, which is about two millimeters deep," says

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  • Choroid plexus carcinomas are malignant brain tumors that originate in the choroid plexus epithelium, which is the gland that produces cerebrospinal fluid.

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  • Instead, there were indications that the cells of the alveolar epithelium, which is the tissue that covers the surface of the air sacs, were rapidly dying.



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