The application of electronspectroscopic imaging (ESI) in biological studies

Abstract

Electronspectroscopic imaging (ESI) offers a means of filtered imaging of specimens resulting in high resolution and depth of field with optimum constrast. Using an integrated imaging electron energy spectrometer (integrated prism/mirror/prism) in a Zeiss-902A transmission electron microscope (TEM), it is possible to select unscattered electrons (ΔE=OeV) or inelastically scattered electrons (ΔE>OeV) to observe biological structures of interest. The contrast in biological specimens is enhanced bythis technique and unstained, ultrathin sections and thick sections can be imaged with optimum contrast and high resolution. This technology can solve many of the problems encountered with staining biological samples (e.g. precipitates or poor contrast) and has proven to be superior to the conventional TEM (CTEM) in many aspects. Virus particles in cultured cells are clearly observed without post-staining. Unstained lipsome and other drug delivery systems can be viewed and measured without negative staining and subsequent deformation and as a result, more accurate sizing information can be obtained. Granules and enzyme reacted precipitates inside unstained cells and tissues can also be observed without staining. Sections that are stained yield finer details than those imaged by CTEM. Figures 1 through 8 obtained with the Zeiss-902A show the quality of ESI and the advantages of using this system of imaging biological specimens.