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.

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

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.

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
References in periodicals archive ?
Colonic polyps were seen in 138 cases and colitis in 18 cases.
The majority of colonic polyps are smaller than 1 cm, with most between 1 and 5 mm.
It is composed of colonic disorders as colonic polyps which show high potential for malignant transformation and extra colonic disorders such as osteoma, desmoid tumors, and epidermoid cysts which are benign tumors, Fortunately, osteomas and skin manifestations precede polyposis, and this facilitates early diagnosis of Gardner's syndrome and gives chance for rapid prophylactic surgical resection of colonic polyps, which is critical and lifesaving for patients with Gardner's syndrome.
Even more importantly, not only is this test good for non-invasively identifying patients who already have colorectal cancer, but it can accurately identify up to 82 percent of patients with advanced colonic polyps, which present the highest risk for developing into colorectal cancers several years later in life.
Mutations in the APC gene are detected in approximately 80% of families with FAP and the rest are detected using colonoscopy which shows numerous colonic polyps at a young age.
Use of anesthesia assistance didn't alter the rate of detection of colonic polyps or the rate of complications such as GI bleeding, perforation, and hospital /ED visits within 30 days.
He subsequently developed multiple rectal and colonic polyps, for which a total colectomy was performed.
Biopsy of colonic polyps revealed cystic dilatation of crypts with oedema of the lamina propria suggesting hamartomatous polyps.
For the given GI complaints of abdominal pain, discomfort, and bleeding PR for which colonoscopy was undertaken, significantly more colonic polyps (p < 0.
Diagnostic colonoscopy did not reveal any colonic polyps.
A study of colonic polyps (precursors to colon cancer) showed that a grape seed preparation reduced the size and number of polyps in mice, and a separate study of grape seed extract showed sound biological mechanisms to explain its blood pressure-lowering effect.