1. Anything resembling a lid or cover. 2. [TA] In anatomy, the portions of the frontal (o. frontale [TA], frontal o. [TA]), parietal (o. parietale [TA], parietal o. [TA]), and temporal (o. temporale [TA], temporal o. [TA]) lobes bordering the lateral sulcus and covering the insula. 3. In parasitology, the lid or caplike cover of the shell opening of operculated freshwater snails in the subclass Prosobranchiata, and of the eggs of certain trematode and cestode parasites. 4. The attached flap in the tear of retinal detachment. 5. The mucosal flap partially or completely covering an unerupted tooth. [L. cover or lid, fr. operio, pp. opertus, to cover]
- o. ilei SYN: ileal sphincter.
- occipital o. a portion of the occipital lobe of the brain demarcated by the simian fissure (sulcus lunatus) when present in humans.
- trophoblastic o. the mushroom-shaped plug of fibrin that fills the aperture in the endometrium made by the implanting ovum.

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oper·cu·lum ō-'pər-kyə-ləm n, pl -la -lə also -lums any of several parts of the cerebrum bordering the sylvian fissure and concealing the insula

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n. (pl. opercula)
1. a plug of mucus that blocks the cervical canal of the uterus in a pregnant woman. When the cervix begins to dilate at the start of labour, the operculum, slightly stained with blood, comes away as a discharge ('show').
2. (in embryology) a plug of fibrin and blood cells that develops over the site at which a developing fertilized ovum has become embedded in the wall of the uterus.
3. (in neurology) one of the folded and overlapping regions of cerebral cortex that conceal the insula on each side of the brain.
4. (in dentistry) a flap of gingival tissue that overlies the crown of a partially erupted tooth.

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oper·cu·lum (o-purґku-ləm) pl. operґcula [L.] 1. a lid or covering structure. 2. one of the insular opercula (q.v.). 3. in fungi, a small cap on an ascus that pops open when the mature organism is ready to eject its spores.

Medical dictionary. 2011.

Look at other dictionaries:

  • Operculum — may refer to: Operculum (animal), a stiff structure resembling a lid or a small door that opens and closes Operculum (gastropod), a lid on the shell of some gastropods Operculum (bryozoa), a lid on the orifice of some bryozoans Operculum (fish),… …   Wikipedia

  • operculum — 1713, from L. operculum cover, lid, from operire to cover, close (see WEIR (Cf. weir)) …   Etymology dictionary

  • Operculum — O*per cu*lum, n.; pl. L. {Opercula}, E. {Operculums}. [L., a cover or lid, fr. operire to cover.] 1. (Bot.) (a) The lid of a pitcherform leaf. (b) The lid of the urnlike capsule of mosses. [1913 Webster] 2. (Anat.) (a) Any lidlike or operculiform …   The Collaborative International Dictionary of English

  • Opercŭlum — (lat., »Deckel«), s. Tafel »Samenformen«; in der Zoologie der Deckel zum Verschließen der Schale bei den Deckelschnecken (s. Schnecken) …   Meyers Großes Konversations-Lexikon

  • operculum — ► NOUN (pl. opercula) Zoology 1) a flap of skin protecting a fish s gills, typically stiffened by bony plates. 2) a plate that closes the aperture of a gastropod mollusc s shell. ORIGIN Latin, lid, covering …   English terms dictionary

  • operculum — [ō pʉr′kyo͞o ləm, ō pʉr′kyələm] n. pl. opercula [ō pʉr′kyo͞olə, ō pʉr′kyələ] or operculums [ModL < L, lid, dim. < operire, to close, shut: for IE bases see OB & APERTURE] any of various covering flaps or lidlike structures in plants and… …   English World dictionary

  • Operculum — Das Operculum einer marinen Schnecke Ein Operculum (lat. „Deckelchen“, Pl. Opercula) ist ein horniger oder kalkiger Deckel, den die Schnecken aus der Gruppe der Vorderkiemer an der Oberseite ihres Fußes tragen. Damit wird die Mündung des Gehäuses …   Deutsch Wikipedia

  • operculum — (female pleopod(s) II). A plate over the branchial chamber of the abdomen of female janiroideans, consisting of the fused second pleopods. The first pleopods are absent in female Janiroidea. In males, pleopods I and II lock together to form an… …   Crustacea glossary

  • operculum — n.; pl. opercula [L. operculum, lid] 1. A lid or flaplike cover. 2. (ANNELIDA: Polychaeta) In certain sedentary forms, a modified tentacle that closes the tube; in some Spirorbidae ( Pileolaria and Janua ) enlarges and serves as a brood pouch. 3 …   Dictionary of invertebrate zoology

  • Operculum — Oper|cu|lum [...kulum] das; s, ...la <aus lat. operculum »Deckel«> deckelartiger Teil eines Organs (Anat.) …   Das große Fremdwörterbuch

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