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ascus

American  
[as-kuhs] / ˈæs kəs /

noun

Mycology.
  • asci
    plural
  1. the sac in ascomycetes in which the sexual spores are formed.


ascus British  
/ ˈæskəs /

noun

  1. a saclike structure that produces (usually) eight ascospores during sexual reproduction in ascomycetous fungi such as yeasts and mildews

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

ascus Scientific  
/ ăskəs /
  • asci
    plural
  1. 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.


Other Word Forms

Noun Inflected Forms

Etymology

Origin of ascus

1820–30; < New Latin < Greek askós bag, sac

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

See Examples For:

A dikaryotic ascus that forms in the ascocarp undergoes karyogamy, meiosis, and mitosis to form eight ascospores.

From Textbooks Jan. 1, 2015

A diploid ascus that forms in the ascocarp undergoes karyogamy, meiosis, and mitosis to form eight ascospores.

From Textbooks Jan. 1, 2015

The zygote undergoes meiosis without cell division, resulting in an ascus with four 1n nuclei arranged in a row.

From Textbooks Jan. 1, 2015

You can count the eight ascospores in this ascus: The tasty, tasty asci of a Morchella sp.

From Scientific American Sep. 5, 2012

The central cell becomes the single ascus, which is characteristic of the species, and the layer which surrounds it constitutes the inner wall of its perithecium.

From Fungi: Their Nature and Uses by M. C. (Mordecai Cubitt) Cooke

In the diagram above, you can see the asci at various stages in meiosis.

From Scientific American Sep. 5, 2012

But some discomycetes — fungi that produce their asci in a cup-like structure in which the fertile surface is completely exposed to the environment — have learned to synchronize their firing.

From Scientific American Sep. 5, 2012

You can count the eight ascospores in this ascus: The tasty, tasty asci of a Morchella sp.

From Scientific American Sep. 5, 2012

In ascomycetes that build their asci inside flask-like structures called perithecia or pseudothecia, the asci take turns snaking to the little opening, poking themselves out, and firing.

From Scientific American Sep. 5, 2012

In the Helvellaceae there is no apothecium but a large irregular fruit body which at maturity bears the asci on its surface.

From Encyclopaedia Britannica, 11th Edition, Volume 11, Slice 3 "Frost" to "Fyzabad" by Various

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