Electron microscopy (EM) is an indispensable tool for the study of ultrastructures of biological specimens. Every electron microscopist would like to process biological specimens for either scanning electron microscopy (SEM) or transmission electron microscopy (TEM) in a way that the specimens viewed under the electron microscope resemble those seen in vivo or in vitro under the light microscope. This is, however, often easier said than done because biological tissue processing for EM requires careful attention of the investigator with regard to the numerous processing steps involved in specimen preparation, such as fixation, dehydration, infiltration, embedding, and sectioning.