polyp

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polyp,

in medicine, a benign tumor occurring in areas lined with mucous membrane such as the nose, gastrointestinal tract (especially the colon), and the uterus. Some polyps are pedunculated tumors, i.e., they grow on stems; others, attached by a broad base, are called sessile. Nasal polyps are usually associated with an allergic condition; since they interfere with breathing, it is advisable that they be removed. Uterine and gastrointestinal polyps are likely to cause bleeding, but, more important, they may undergo malignant degeneration and for this reason are also usually removed.
The Columbia Electronic Encyclopedia™ Copyright © 2013, Columbia University Press. Licensed from Columbia University Press. All rights reserved. www.cc.columbia.edu/cu/cup/
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Polyp

 

a morbid growth that develops on mucosa of the respiratory tract, uterus, stomach, large intestine, rectum, and urinary bladder. Polyps are villous formations of various shapes; sometimes pear-shaped, they are usually broad-based or pedunculated. They may ulcerate and cause hemorrhages. Modern medical practice considers polyps precancerous, and therefore they are surgically removed.


Polyp

 

the common name for the predominantly benthic form of coelenterates. In metagenetic forms, that is, in hydrozoans (except hydras) and scyphozoans, polyps are capable only of vegetative reproduction, forming either medusae (in hydrozoans by budding, in scyphozoans by transverse division) or other polyps. Sexual reproduction is characteristic in such forms only in individuals of the medusa phase—free-swimming individuals or individuals remaining attached to the polyp. In homogenetic forms (hydrida and anthozoans), the polyps are capable of both sexual and vegetative reproduction. With sexual reproduction, larvae develop from the eggs and are transformed into polyps.

Polyps usually are cylindrical and measure from several millimeters to several centimeters tall (rarely up to 1 m). The upper part of the body contains the mouth, which is surrounded by tentacles. The base serves as a foot by which the polyp attaches itself to the substrate (in solitary forms) or to the colony (in colonial forms). There is often a hard external or internal skeleton of organic matter or limestone. The nervous system, which is developed considerably less than in the medusa, is in the form of a subepithelial nerve ganglion. Sex glands are present only in homogenetic forms and are located in the ectoderm (in Hydrida) or in the entoderm (in anthozoans). Sexual products are eliminated through ruptures in the walls of the gonads. In rare cases (in some actiniae), development occurs in the gastral cavity of the maternal body.

Polyps, except for hydras and a few related forms, are marine organisms. The majority lead a sedentary life; many form colonies. Movements are limited by the extension and contraction of the body and tentacles. Some solitary forms, hydras and actiniae, move slowly along the substrate; a few actiniae inhabit the depths. Polyps feed predominantly on animal substances, usually capturing their prey with their tentacles.

REFERENCES

See references under COELENTERATA.

D. V. NAUMOV

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.

polyp

[′päl·əp]
(invertebrate zoology)
A sessile cnidarian individual having a hollow, somewhat cylindrical body, attached at one end, with a mouth surrounded by tentacles at the free end; may be solitary (hydra) or colonial (coral).
(medicine)
A smooth, rounded or oval mass projecting from a membrane-covered surface.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

polyp

1. Zoology one of the two forms of individual that occur in coelenterates. It usually has a hollow cylindrical body with a ring of tentacles around the mouth
2. Pathol a small vascularized growth arising from the surface of a mucous membrane, having a rounded base or a stalklike projection
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005
References in periodicals archive ?
Table 1 describes the findings from literature over the last two decades regarding cases of solitary juvenile polyp with adenomatous changes (one case without such changes, but with changes consistent with signet ring cell carcinoma in an adult patient).
In summary, we describe the occurrence of adenomatous change in a sporadic juvenile polyp. Sporadic juvenile polyps are lesions with potential for neoplastic and even malignant transformation.
anal fissure or juvenile polyp. Sometimes these symptoms point to more serious and life-threatening conditions 20.
We found juvenile polyp in 58.75 % of patients which is quite close to the findings of other studies from Pakistan like Wajeehuddin and Ali Raza Brohi found it to be 56.25% 25.
A solitary juvenile polyp with hyperplastic and adenomatous glands.
Rashid et al., "Genetic alterations and epithelial dysplasia in juvenile polyposis syndrome and sporadic juvenile polyps," American Journal of Pathology, vol.
vectensis, PCR primers designed from the nucleic acid sequences encoding both predicted proteins were used to amplify products from a template derived from RNA isolated from juvenile polyps. Products of the predicted sizes were amplified from regions corresponding to the Lam NT domain, EGF-like domains, and the FN3 domains of Nemvel: 199904 and Nemvel:59990 (Fig.
In situ hybridization with an usherin-specific riboprobe (nN2A) confirms that usherins are expressed both in planulae and in juvenile polyps (Fig.
Juvenile polyps are hamartomatous epithelial retention polyps and are nonneoplastic.
Juvenile polyps. Although juvenile polyps are nonneoplastic, juvenile and adenomatous polyps sometimes occur concomitantly.
In these juvenile polyps, the cushion-like tissue disappeared into the endoderm of the aboral half, and many digestive gland cells developed in the endoderm of the oral half of the hydranth (Fig.
From 2-4-h-old larvae to juvenile polyps, the number of Als decreased significantly (Table 1); however, the number of AIs in an aboral tentacle of the newly settled individuals varied very much (from 0 to 40).

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