Fine structural studies of the Chrysosporium state of Renispora flavissima

Aspects of the fine structural characteristics of conidial and hyphal cells of the imperfect Chrysosporium state of the newly reported gymnoascaceous fungus, Renispora flavissima, are described and illustrated by electron micrographs of ultrathin sections. Preservation of the substructure of the thick-walled, smooth to tuberculate conidia was best achieved after fixation in permanganate. The conidial wall consisted of two conspicuous zones (or layers) of varying thickness, texture, and electron opacity. The tuberculate ornamatations arose as extensions of the electron opaque outer zone. The outer layer(s) of the conidial wall proper was continuous with an outer wall layer of the conidiogenous hypha. The conidial cytoplasm was cytologically complex containing numerous but typical fungal inclusions and organelles scattered throughout. This ultrastructural feature of the tuberculate conidia of the Chrysosporium sp. differs from that observed for the morphologically similar large tuberculate conidia of the zoopathogenic Histoplasma capsulatum.