Potassium permanganate is an excellent alternative to osmium tetroxide in freeze-substitution

• DOI: 10.1007/s00418-021-02070-0
• Publication Date: 2022-01-11T12:03:04Z
• Authors: Martin Schauflinger; Tim Bergner; Gregor Neusser; Christine Kranz; Clarissa Read
• Keywords: Osmium tetroxide; Potassium permanganate; Osmium; Uranyl acetate; Permanganate

High-pressure freezing followed by freeze-substitution is a valuable method for ultrastructural analyses of resin-embedded biological samples. The visualization lipid membranes one the most critical aspects any study and can be especially challenging in high-pressure frozen specimens. Historically, osmium tetroxide has been preferred fixative staining agent lipid-containing structures solutions. However, not only rare expensive material, but also volatile toxic. Here, we introduce use combination potassium permanganate, uranyl acetate, water acetone as complementing reagents during process. This mix imparts an intense en bloc stain to cellular ultrastructure membranes, which makes poststaining superfluous well suited block-face imaging. Thus, permanganate effectively replace solution without sacrificing quality preservation.