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[as-kuh s] /ˈæs kəs/
noun, plural asci
[as-ahy, -kahy, -kee] /ˈæs aɪ, -kaɪ, -ki/ (Show IPA).
the sac in ascomycetes in which the sexual spores are formed.
1820-30; < New Latin < Greek askós bag, sac Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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British Dictionary definitions for ascus


noun (pl) asci (ˈæsaɪ; ˈæskaɪ)
a saclike structure that produces (usually) eight ascospores during sexual reproduction in ascomycetous fungi such as yeasts and mildews
Word Origin
C19: from New Latin, from Greek askos bag
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
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Word Origin and History for ascus

"sac in certain fungi," 1830, Modern Latin, from Greek askos "leather bag, wine skin," of unknown origin.

Online Etymology Dictionary, © 2010 Douglas Harper
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ascus in Medicine

ascus as·cus (ās'kəs)
n. pl. as·ci (ās'ī', -kī')
A membranous, often club-shaped structure in which typically eight spores are formed through sexual reproduction of ascomycetes.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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ascus in Science
Plural asci (ās'ī', -kī')
A membranous, often club-shaped structure inside which ascospores are formed through sexual reproduction in species of the fungi known as ascomycetes. The ascus is unique to ascomycetes and distinguishes them from other kinds of fungi. Asci are formed when two hyphae that are sexually compatible conjugate. Each ascus typically develops eight ascospores. Asci swell at maturity until they burst, shooting the ascospores into the air.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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Encyclopedia Article for ascus


a saclike structure produced by fungi of the phylum Ascomycota (sac fungi) in which sexually produced spores (ascospores), usually four or eight in number, are formed. Asci may arise from the fungal mycelium (the filaments, or hyphae, constituting the organism) without a distinct fruiting structure, as in the leaf curl fungi; it may arise within a fruiting structure (ascocarp) that may be exposed, as in the molds and powdery mildew fungi; or it may be imbedded in a compact structure (stroma), as in the ergot and black knot fungi. In the case of yeasts, a single cell converts to an ascus.

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Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.
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