Scanning electron microscopy of cryofixed and critical point-dried Coprinus cinereus

The external morphology of spore-bearing gills of the agaric, Coprinus cinereus, has been studied, employing the Hexland cryo-apparatus attached to a Cambridge Stereoscan electron microscope. To assess the advantages of looking at frozen-hydrated material, a comparison has been made with similar tissue which had been chemically fixed and critical point-dried. Although good preservation of the basidiospores was achieved by the latter technique, the basidia were seen to have a wrinkled appearance and the cystidia were sometimes damaged with portions missing and never attained the ‘full-blown’ appearance of those on cryofixed gills. Additionally what appears to be a mucilaginous layer covering the gills, largely absent or indistinct in critical point-dried specimens but with remnants remaining as a fibrous network on the basidiospores, was preserved in frozen-hydrated ones.