polyp

(redirected from adenomatous polyp)
Also found in: Dictionary, Thesaurus, Medical.
Related to adenomatous polyp: sessile polyp, hyperplastic polyp

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 ?
Most common neoplastic polyps are adenomas or adenomatous polyps, which arise due to dysplastic proliferation and have a potency to progress to cancer.
These include Turcot syndrome, an inherited condition in which people are at an increased risk of adenomatous polyps (and thus, colon cancer) and brain tumors, and Peutz-Jeghers syndrome, a condition that leads to freckles around the mouth and sometimes on the hands and feet, as well as large polyps in the digestive tract and an increased risk of colon and other cancers at a young age.
Colorectal cancer develops from non-cancer polyps called adenomatous polyps.
Mixed hyperplastic adenomatous polyps--an underdiagnosed entity: report of a case of adenocarcinoma arising within a mixed hyperplastic adenomatous polyp.
Hundreds to thousands of adenomatous polyps in the colon and rectum characterize this disease.
If you take people with colon cancer or adenomatous polyps and remove the cancer or polyp, their colons are still abnormal," says Mason.
That finding suggested that the origination and development of adenomatous polyps proceeded through a top-down mechanism.
Furthermore, there is some evidence to suggest that cancers of the small and large bowel both arise from adenomatous polyp precursor lesions, suggesting the adenoma-carcinoma sequence is relevant to both sites.
The most recent are 3 large, multicenter prospective trials comparing the sensitivity and specificity of CTC against colonoscopy for adenomatous polyp detection.
Of those surveyed who collect QI data, majorities cited scope withdrawal time (62%) and rate of adenomatous polyp detection (52%) as indicators they capture most frequently.
Other polypoidal lesions we encountered in this study were Leiomyoma (3), Adenomatous polyp (1), Adenoleiomyoma (1) and Nabothian cyst(2).