Three-Dimensional Structure Reconstruction by High Voltage Electron Microscopy of Biological Specimens

A major advantage of the high voltage electron microscope (HVEM, accelerating voltage 1000 kV) is its ability to produce high quality images of slices of enbedded biological tissue or whole mounts of cells 1 μm or greater in thickness. Several workers have been trying to exploit this feature in studies of cell structures using the HVEM facility at the University of Colorado. When the right combination of thickness and contrast has been obtained, the resulting micrographs can be quite remarkable both for the quantity of information they contain and for the directness and clarity with which the three-dimensional information can be seen.For purposes of discussion, one can group the kinds of biological specimens and HVEM approaches to their study into three classes. First there are isolated cells or cell parts that can be fixed, mounted directly on support films, dried by the critical point or other appropriate method, and examined immediately without embedding or other treatment.