Comparative effect of osmium tetroxide and ruthenium tetroxide on Penicillium sp. hyphae and Saccharomyces cerevisiae fungual cell wall ultrastructure / Efecto comparativo del tetróxido de osmio y del tetróxido de rutenio como fijadores sobre la ultraestructura de la pared celular de hongos

ABSTRACT

The fungal cell wall viewed through the electron microscope appears transparent when fixed by the conventional osmium tetroxide method. However, ruthenium tetroxide post-fixing has revealed new details in the ultrastructure of Penicillium sp. hyphae and Saccharomyces cerevisiae yeast. Most significant was the demonstration of two or three opaque diverse electron dense layers on the cell wall of each species. Two additional features were detected. Penicillium septa presented a three-layered appearance and budding S. cerevisiae yeast cell walls showed inner filiform cell wall protrusions into the cytoplasm. The combined use of osmium tetroxide and ruthenium tetroxide is recommended for post-fixing in electron microscopy studies of fungi.