Definition of osmium tetroxide in US English:

osmium tetroxide


  • A poisonous pale yellow solid with a distinctive pungent smell, used in solution as a biological stain (especially for lipids) and fixative.

    Chemical formula: OsO₄

    • ‘The tissue is then placed for 8 to 10 days in a solution containing potassium chlorate, osmium tetroxide, formaldehyde, and glacial acetic acid.’
    • ‘For ultrastructural studies, formalin-fixed tumor samples were washed, postfixed in buffered osmium tetroxide, dehydrated, and embedded in epoxy resin.’
    • ‘The cytoplasm of medullar cells, fixed in osmium tetroxide, stained more deeply with toluidine blue than that of cortical cells.’
    • ‘Experts say a bomb with the chemical osmium tetroxide would have wiped out the first police and rescue workers on the scene.’
    • ‘Electron microscopy was performed with fresh tissues fixed in glutaraldehyde and postfixed in osmium tetroxide.’