Improved ultrastructural preservation of yeast cells for scanning electron microscopy

The processing of yeast cells for scanning electron microscopy by conventional sequential fixation with glutaraldehyde and osmium tetroxide and subsequent dehydration and critical point-drying caused pronounced deformation and visible shrinkage in all basidiomycetous and ascomycetous yeast strains studied. The mean cell diameter decreased to nearly 60 and 70%, respectively. After an additional sequential fixation with 1% tannic acid and 0.5% uranyl acetate the cell shrinkage was significantly reduced, but the most important result was a considerable reduction of wrinkling and deformation of the yeast cells.