Electron microscopy: More than just a pretty picture

In the 1990s, it might have been thought that, for biological sciences, electron microscopy (EM) was a technique that had had its day. The majority of cellular ultrastructure had been described, and many EM units were closed. However, new developments in instruments, including computer control of microscope columns and stages, the introduction of digital cameras with freely avail able software for image processing and manipulation and improvements in specimen prepara tion techniques have led to a resurgence in the use of EM and wider applicability in the biological sciences. This article aims to show how, even in its routine use, EM can provide further insight into cell biology studies, to show how EM is being used to provide fundamental information about the localization and relationships of molecules within cells through the technique of immuno cytochemistry and to introduce techniques such as EM tomography that are providing unrivalled information about structure–function relationships within cells.