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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.



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.



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.


See references under COELENTERATA.



(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).
A smooth, rounded or oval mass projecting from a membrane-covered surface.


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
References in periodicals archive ?
One is a balance problem, since the middle ear has been affected by both the polyp and its removal.
The prospective study, led by Dr Yuichi Mori from Showa University in Yokohama, Japan, involved 250 men and women in whom colorectal polyps had been detected using endocytoscopy.
The overall histopathology of the lesion was reported as "lymphangiectatic fibrolipomatous polyp," and the left tonsillectomy material was reported as "chronic tonsillitis".
Polyp size has not been considered as an adequate exclusion criteria for neoplasia or malignancy (18).
Nasal polyps are considered the most common of these.
Demographic data, such as gender and age of the patients, and clinical information, such as site of polyp, were obtained from the Hospital Information System (TrakCare).
In the present study out of 88 cases of endometrial polyps, 70 (Submucosal leiomyoma), 11 (Benign endometrial polyps), 1 case of endometrial polyp with atypical hyperplasia and 6 cases of endometrial carcinoma were diagnosed on histopathology.
For instance, those in the rectum are likely to have large bundles of smooth muscle extending into the base from the muscularis mucosae, a change often considered to be a manifestation of prolapse, yet it is very difficult to understand why a tiny polyp should undergo prolapse changes.
We have provided a comprehensive review of ureteral fibroepithelial polyp described in the English language literature since 1980.
By searching published articles in the PubMed database, using keywords "antrochoanal polyp" for the ten year period (October 2004 - July 2014), 74 articles were found which contain terms "nasal", "choanal" and "antrochoanal" polyp in their headlines.
Impaired water-mineral balance may be explained by the fact that predisposition to absorb sodium and chloride ions is more developed in the epithelium of a polyp than in the epithelium of unchanged nasal conchas [30].
In case of abdominal pain or gastrointestinal bleeding, endoscopic examination is necessary to localize the bleeding polyp so that they can be resected.