• WordNet 3.6
    • n epithelium membranous tissue covering internal organs and other internal surfaces of the body
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Webster's Revised Unabridged Dictionary
    • n Epithelium (Anat) 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.
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Century Dictionary and Cyclopedia
    • n epithelium 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. The usual meaning of the word, however, is somewhat wider than this, and includes all tissues similar in structure to the above. It embraces the proper tissue of secreting glands, whether derived from the hypoblast, as in the case of the gastric and intestinal glands, the liver and the pancreas, or from the epiblast, as in the case of the sudoriparous, sebaceous, and mammary glands, or from the mesoblast, as in the case of the kidneys, ovaries, and testes; it is applied, moreover, to the ependyma of the cerebrospinal ventricular cavities and to the epidermis itself. With what seems a distinct widening of its meaning, the term is not infrequently employed to designate the endothelium of blood- and lymph-channels and of serous membranes. The epithelium is thus the covering of all free surfaces, mucous, external, and even serous, and forms the glands and other organs derived from these coverings. Epithelial tissue consists of cells, usually compactly set; the nuclei are usually distinct, with an intranuclear network and nucleoli. The intercellular substance is scanty, often inappreciable, and is called cement. It contains no blood-vessels or lymphatics, but nerve-fibrils extend into it. The epithelial tissue, forming the outermost covering of free surfaces, is favorably situated for performing protective and secreting functions. The protective function is not only exhibited by the general layer of easily replaced cells coating the mucous membrane and outer skin, hut in the latter case by a peculiar tendency to form keratin, and this results in a quite impervious outer horny layer, which guards against minor violence, the absorption of deleterious substances, and the invasion of pathogenic bacteria, as well as in the development of such especial means of protection as scales and feathers, hair and nails. This chemical feature of that epithelium which is especially devoted to protection, the production of keratin, can be matched by no single peculiarity on the part of the secretory epithelium; for that must respond equally whether it is called upon to eliminate waste products, or to elaborate digestive ferments, or to manufacture milk. It is probable that some of the cells lining the digestive tract have an active absorptive function with reference to the products of digestion, and that they select and take up certain substances from the intestine, and after more or less elaboration pass them on to the blood- or lymph-channels. This forms a kind of inverted secretion. The epithelial cells of secreting glands are, in part at least, under the direct control of the nervous system. Whether epithelial cells having a purely protective function are, as regards their nutrition, under similar control is still a question. See cuts under Malpighian and villus.
    • n epithelium In ornithology, specifically, the dense, tough cuticular lining of the gizzard. It is sometimes even bony, and sometimes deciduous.
    • n epithelium 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.
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Chambers's Twentieth Century Dictionary
    • n Epithelium ep-i-thē′li-um the cell-tissue which invests the outer surface of the body and the mucous membranes connected with it, and also the closed cavities of the body
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Webster's Revised Unabridged Dictionary
NL., fr. Gr. 'epi` upon + nipple
Chambers's Twentieth Century Dictionary
Gr.,—epi, upon, thēlē, nipple.


In literature:

THE EPIDERMIS is a stratified epithelium.
"Diseases of the Horse's Foot" by Harry Caulton Reeks
The growth of epithelium may be stimulated by a 6 to 8 per cent.
"Manual of Surgery" by Alexis Thomson and Alexander Miles
The papillae of the tongue are large and distinct, and covered with separate coats of epithelium.
"The People's Common Sense Medical Adviser in Plain English" by R. V. Pierce
The general name for such tissues is epithelium.
"Text Book of Biology, Part 1: Vertebrata" by H. G. Wells
The process begins in one great class of cells, the epithelium of the secreting glands.
"Preventable Diseases" by Woods Hutchinson
It now lies deep in the tissue of the floor of the pharynx, entirely separated from the pharyngeal epithelium.
"Development of the Digestive Canal of the American Alligator" by Albert M. Reese
It is covered by stratified squamous epithelium.
"Manual of Surgery Volume Second: Extremities--Head--Neck. Sixth Edition." by Alexander Miles
The lining or covering tissues, both internal and external, are known as epithelium.
"Special Report on Diseases of Cattle" by U.S. Department of Agriculture
They contain large quantities of disintegrated epithelium from the mucous membrane of the intestines.
"Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 3" by Various
Besides, there would always remain an incalculable and very large amount externally, in the nonabsorptive epithelium.
"Handbook of Medical Entomology" by William Albert Riley
The inner face of this muscular skin is lined by a layer of epithelium.
"Encyclopaedia Britannica, 11th Edition, Volume 8, Slice 10" by Various
The epithelium is in three or more layers, the superficial one being very characteristic.
"Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 6" by Various
There are several varieties of epithelium.
"The New Gresham Encyclopedia" by Various
The epithelium seems to be left intact.
"Psychotherapy" by James J. Walsh
This layer probably includes, or consists of, germinal epithelium.
"Natural History of the Ornate Box Turtle, Terrapene ornata ornata Agassiz" by John M. Legler
The tubular epithelium shows little or no demonstrable changes.
"Arteriosclerosis and Hypertension:" by Louis Marshall Warfield
Fibrinous exudations on mucous surfaces, according to Weigert, can only take place when the epithelium is destroyed.
"A System of Practical Medicine by American Authors, Vol. I" by Various
The layer of pigment epithelium which is present in the human eye, is present also in that of the trout.
"Old Flies in New Dresses" by Charles Edward Walker
The stomach is simple in form, and the epithelium of the oesophagus does not extend into it as is the case with the Horse and Rhinoceros.
"The Cambridge Natural History, Vol X., Mammalia" by Frank Evers Beddard
External to this tunic is the superficial layer of the germinal epithelium, which forms what has been spoken of as the pseudo-epithelium.
"The Works of Francis Maitland Balfour, Volume 1" by Francis Maitland Balfour

In news:

External auditory canal cholesteatomas, which result from the deposition of squamous epithelium deep to the skin of the external canal, can be caused by postsurgical implantation, radiation, or trauma.
External auditory canal cholesteatomas , which result from the deposition of squamous epithelium deep to the skin of the external canal, can be caused by postsurgical implantation, radiation, or trauma.
Steven Schwartz and colleagues' study on transplantation of retinal pigment epithelium derived from human embryonic stem cells (hESCs) for the treatment of macular degeneration (Feb 25, p 713).
Recurrent respiratory papillomatosis is a benign neoplastic process involving squamous epithelium of the respiratory tract, typically the vocal folds.
1 add to the evidence from in-vitro and animal studies in suggesting that transplantation of retinal pigment epithelium derived from human embryonic stem cells could be used to treat macular degeneration.
A Pattern Dystrophy of The Retinal Pigment Epithelium .
External hemorrhoids (a single lesion is shown here) are found below the dentate line (the division between squamous epithelium distally and transitional columnar epithelium proximally) and so are covered by skin.
Ret -Dependent Cell Rearrangements in the Wolffian Duct Epithelium Initiate Ureteric Bud Morphogenesi.