the sac in ascomycetes in which the sexual spores are formed.
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How to use ascus in a sentence
The yellow spores are very minute, each ascus containing eight of them, and they are divided by a transverse partition or septum.An Elementary Text-book of the Microscope | John William Griffith
This operculum may be the more readily seen when the ascus is coloured by a drop of tincture of iodine.
Each ascus contains a definite number of sporidia, which are sometimes coloured.
The sporidia are usually eight in each ascus, either arranged in single or double rows, or irregularly grouped together.
Other species contain linear sporidia, which are often the length of the ascus, and may either be simple or septate.
British Dictionary definitions for ascus
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
Scientific definitions for ascus
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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