cystidium

As the gill expands the cystidium breaks away from one gill and projects from the other gill.

A cystidium (plural cystidia) is a relatively large cell found on the hymenium of a basidiomycete (for example, on the surface of a mushroom gill), often between clusters of basidia.

The length of these cells is typically 100-130 m, with a width of 35-45 m. Before the cap expands, each cystidium completely branches an interlamellar space, with both ends attached to the gills, help together by clasping paraphyses.

In his 1837 paper Sur le hymenium des champignons, he provided an early, comprehensive description of the basidium and cystidium of basidiomycete fungi, and was able to establish the role that the basidium played in spore production.