The ultrastructure of starch from ultrathin sectioning in melamine resin

A method is described whereby unstained native or litnerized starch granules were embedded in Nanoplast resin before being ultrathin sectioned and observed by transmission electron microscopy. As these sections were initially devoid of contrast, a mild HCl hydrolysis was applied in order to reveal the location of the granules. During this treatment, the embedding resin was etched preferentially while the granules were left almost intact. This method allowed an easy recording of electron diffraction diagrams of starch when the microscopy was done under frozen hydrated conditions. Low dose images with good contrast could also be obtained from unstained and unshadowed specimens.