(redirected from polypoid)
Also found in: Dictionary, Thesaurus, Medical, Wikipedia.
Related to polypoid: polypoid cystitis


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 ?
Major Finding: In women, nonpolypoid colorectal neoplasms are approximately three times as likely as polypoid lesions to contain advanced histology.
At the time of surgery, the right middle meatal polypoid mass was seen to be originating in the right frontal recess and was carefully resected with a microdebrider at its superior base in the frontal recess (figure 1, D).
Cystoscopic abnormalities in EC ranged from mucosal erythema to elevated, velvety, polypoid, oedematous, clearly aggregating, and invasive-appearing masses.
Early cancers appear as focal enhancing mucosal thickening or as polypoid lesions (Figure 1).
However 2 types of polypoid lesions are worthy of mention: the prostatic urethral polyp and the fibroepithelial polyp.
His chest x-ray was normal, but computed tomography (CT) scan of the abdomen revealed a large polypoid mass lesion in the right colon extending from the ileo-caecal valve with lumen-narrowing and mildly enlarged pericolic lymph nodes.
These tumors may manifest as intraluminal polypoid or sessile masses, eccentric narrowing of the airway, or circumferential wall thickening on CT.
The model assumed that 85% of colorectal cancers develop from a polypoid precursor, and the remaining 15% are de novo tumors.
Most tumors are sessile or polypoid and located in the subendocardium or subepicardium.
Similar to the primary tumors of the tongue, metastatic lesions to this organ may be ulcerated or polypoid.
Unlike the classic blue, brown, or black lesions that gynecologic surgeons are accustomed to seeing in adults, biopsy-proven endometriosis in adolescents often takes the form of clear vesicles or small red polypoid hemorrhagic or petechial lesions.