Cell form, function and lineage in the hymenia of Coprinus cinereus and Volvariella bombycina

A hymenial cell initial was binucleate in Coprinus cinereus but uninucleate in Volvariella bombycina. Paraphyses and facial cystidia remained binucleate in C. cinereus, but marginal cystidia were the apical cells of branches from the multinucleate gill trama. becoming swollen when gills pulled away from their connection to the stipe, and were multinucleate. In V. bombycina. all mature cystidia were multinucleate but as a result of multiple mitoses. Meiotic DNA synthesis, as determined by fluorescence microspectrophotometry on DAPI-stained nuclei, was found to take place before karyogamy in C. cinereus and possibly after karyogamy in V. bombycina. The nature of fungal cell differentiation is discussed, and comparisons are made with published information about hymenium structure of Agaricus bisporus. 221