Acetylation as a means of selectively blocking vicinal diols of carbohydrates in electron microscopy

Acetylation for selectively blocking the vicinal diols of carbohydrates has successfully been applied to ultrathin sections in electron microscopy. From buffered glutaraldehyde fixed rat colon and jejunum tissues embedded in LR-White, ultrathin sections were cut, treated with hot acetic anhydride in pyridine and then reacted for periodic acid-thiocarbohydrazide-silver proteinate (PA-TCH-SP). The PA-TCH-SP reaction of all the glycoproteins and glycogen involved in the colonic and jejunal epithelia was selectively blocked by prior acetylation, providing a means of substantiating the presence of vicinal diols of carbohydrates in electron microscopy.