Impregnation of biological material by ZnI2-OSO4, KI-OSO4 and NaI-OSO4 mixtures for electron microscopic observations: chemical interpretation of the reaction.

Alkaline iodide-osmium tetroxide mixtures were used in an electron microscopic study of plant cells and gave better results in the preservation of the cell structure in contrast to the cell structure observed when ZnI2-OSO4 mixtures are used. The electron density observed in the reactive sites of the cell by OSO4-iodide mixtures is controlled by the presence and oxidation state of iodine that acts as a regulator of the potential redox of the reaction of OSO4 with the biological material.