Ascus

Definition

An ascus is a sac-like structure in which spores (ascospores) are formed during the sexual reproduction of ascomycete fungi. Typically, an ascus contains eight ascospores resulting from meiosis followed by a mitotic division.

5 Must Know Facts For Your Next Test

1. Asci are characteristic of the Ascomycota division, also known as sac fungi.
2. The formation of asci occurs within specialized fruiting bodies called ascocarps.
3. Each ascus usually contains eight ascospores, but this number can vary among species.
4. The development of asci is a critical step in the life cycle and sporulation process of ascomycetes.
5. Asci can take different shapes, such as cylindrical or spherical, depending on the fungal species.

Review Questions

• What type of spores are contained within an ascus?
• In which division of fungi are asci primarily found?
• How many ascospores does a typical ascus contain?

Related terms

Ascospore: A spore produced within an ascus during the sexual reproduction of Ascomycota fungi.

Ascocarp: A fruiting body that contains multiple asci where spore development occurs.

Ascomycota:

A division of fungi characterized by the formation of asci and ascospores during sexual reproduction.