Crozier (mycology)

A crozier is an anatomical feature of many fungi in the phylum Ascomycota that forms at the base of asci and looks like a hook-topped shepherd’s staff or stylized religious crosier.

[1][2] Croziers resemble and function similarly to clamp connections on the dikaryotic hyphae of Basidiomycota.

Each nucleus divides, resulting in the formation of a pair of compatible nuclei, i.e. a dikaryon, in the ascus, which is now the penultimate space.

The tip of the crozier then fuses with the basal cell and walls itself off from the ascus by the formation of a septum.

Below the base of the ascus, these nuclei migrate together into a growing side branch which is capable of repeating the ascus-crozier formation process indefinitely.