Scanning Electron Microscopy

In studying, describing, and classifying diatoms, the scanning electron microscope (SEM) has become an indispensable tool for diatom taxonomists (1,2). The diatom surface, composed of organic materials and silica, provides excellent working material for use in scanning electron microscopy when properly preserved and fixed. The siliceous cell wall, also called a frustule, is often covered with organic material that can obscure key morphological details if not properly removed prior to viewing with the SEM (3). There are several procedures that will allow diatoms to be stripped of their outer organic coverings while keeping the frustule intact. Here, we describe the most common techniques used for SEM analysis of diatoms. Whenever possible, we have included slight derivations suggested in the current literature to these classical techniques.