polyp

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Related to polypus: pedunculated 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 ?
If the poet is to be a Kraken, it seems, he must achieve that point of identification on rather specialized terms, through a semantic trick, a verbal illusion, in which one kind of polypus substitutes for another.
These animals are apparently at, or near, the ocean floor-but then, as one kind of polypus becomes another, there is a further bottoming-out, by which reader and Kraken end up in a peculiar minimalist harmony, back, perhaps, at the beginning of life (however life may have begun, whether by God's hand or nature's).
The regressive polypus, that soothing and somnolent hybrid, is replaced altogether by a more spectacular creature, susceptible to intensive investigation.
The more ancient the (presumed) polypus seems, the more he acquires a common ground with a chambered Victorian heart like Tennyson's.
This approach is also used in 4-Rhinosporidiosis, 3-Bleeding polypus and 1-Granuloma pyogenicum, 1-Meningoencephalocele; 1 Pleomorphic adenoma, 1-Angiomyxomatous polyp cases.
The "mighty Polypus," Albion's out-of-control proliferation in his fallen state, is usually interpreted as fully negative, but Gigante argues that, like Schiller, "Blake ultimately reappropriated [it] as a symbol of revolutionary power" (129), a reading based upon Orc's link to the polypus in Milton and Blake's consistent valuing of a life-giving, "epigenetic" translucence over a rigid opacity.
This mighty Polypus, a serpentine embodiment of imperial desire, originates in Albion and assimilates to Albion, as Albion roots itself in every nation.
Mimicking the imperial ambitions of England, the Polypus expands into India and the Far East by way of Palestine and the Near East.
As a force that originates "from below," the hydra has come to represent precisely that possibility of which Blake's polypus is a tantalizing mirror image: a revolutionary, organized, global connection between oppressed people.
This hydra is all the imaginative possibilities of the Polypus made good, a "means of exploring multiplicity, movement, and connection, the long waves and planetary currents of humanity" (6).
A commentary of about 1810 speaks with horror as London extended its "great polypus arms over the country round," where brick kilns "poisoned" the salubrious air, leaving an overwhelming odor of carrion (a smell of death so powerful that it caused nausea).
Ololon's final appearance creates an organic relationship between writing and orality, the productions of Golgonooza and Eternity, as both are mediated through the materiality (represented in the Polypus) of fallen time and space (represented in the Mundane Shell).