OSMIUM TETROXIDE AND THE MARCHI METHOD: REACTIONS WITH POLAR AND NON-POLAR LIPIDS, PROTEIN AND POLYSACCHARIDE

Abstract

1. The reactions of tissues with OsO4 and the Swank-Davenport KClO3-OsO4 (Marchi) reagent have been studied by blockade of the reducing groups of unsaturated lipid, protein and polysaccharide. Only blockade of the —CH=CH— bond prevented osmiophilia after brief staining (18 hr.). 2. Tissue-protein is neither stained nor demonstrably impregnated after brief treatment with OsO4. 3. Chromatographic separation of degenerating myelin revealed that the Marchi-substance is eluted in the esterified cholesterol fraction. 4. Unsaturated lipid but not protein or polysaccharide are stained by brief treatment with OsO4. The Marchi reaction distinguishes hydrophilic from hydrophobic unsaturated lipid.