ascus

American  

[as-kuhs] / ˈæs kəs /

noun

Mycology.

plural

asci

1. the sac in ascomycetes in which the sexual spores are formed.

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ascus British  

/ ˈæskəs /

noun

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

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ascus Scientific  

/ ăs′kəs /

plural

asci

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.

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Etymology

Origin of ascus

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

Example Sentences

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

From Textbooks • Jan. 1, 2015

In each ascus, two or more haploid ascospores fuse their nuclei in karyogamy.

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

That is, inside the ascus, a diploid fungal nucleus undergoes meiosis — or sexual, reductive cell division — to produce ascospores.

From Scientific American • Sep. 5, 2012

The mildews may be divided into two genera: Podosphæra, with a single ascus in the spore fruit; and Erysiphe, with two or more.

From Elements of Structural and Systematic Botany For High Schools and Elementary College Courses by Campbell, Douglas Houghton