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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 ?
Skin tags are generally polypoid, with a flattened epidermis overlying loose collagen bundles and an absence of adnexal structures.
Clinically, it can be classified into superficial, nodular, pigmented, ulcerating, cystic, and sclerosing patterns.[1] Histological variants are nodular, micronodular, fibroepithelial, adenoid, morphea form, and infiltrative types.[3] An exceptional appearance as a polypoid lesion is very rare.
Polypoid melanoma and superficial spreading melanoma different subtypes in the same lesion.
With these pathologic features, the final evaluation of the polypoid mass was reported as myxoma.
On pathological examination, 1.4x1-cm polypoid lesion covered with mucosa was observed macroscopically.
Ganglioneuromatosis polyposis is distinguished by numerous sessile or pedunculated mucosal and/or submucosal lesions showing greater variability in neural, supportive, and ganglion cell content with demarcation compared to polypoid ganglioneuromas.
Caption: Figure 4: Coronal, axial, and sagittal contrast enhanced CT image demonstrates a polypoid mass in the base of the cecum representing a cecoappendiceal intussusception, mimicking a polyp or neoplasm.
19 Irregular vaginal Polypoid 2.5 bleeding endometrial mass McCluggage 53 Incidental Intramural 2.5 et al.
Nakayama, "Diagnosis and operative indications for polypoid lesions of the gallbladder," Archives of Surgery, vol.
Endoscopic examination results revealed a big, yellow, lobular polypoid lesion in the right nasal cavity and multiple polypoid masses in the left nasal cavity.
If the tumor originates from the cervix, the tumor is commonly seen as a polypoid tissue protruding from the external cervical ostium like a cervical polyp on gross evaluation (3,4).
Since postoperative follow-up revealed no decrease in tumor markers, total colonoscopy was performed on the patient, which revealed several discrete polypoid lesions in the transverse and ascending colon, measuring 5–10 mm in diameter.