Immunoelectron Microscopy and the Molecular Ultanstructure of Cells

An important component in the armamentarium of a biological electron microscopist is immunoelectron microscopy (IEM), the use of appropriately tagged antibodies to immunolabel and localize specific molecules in cells and tissues in electron microscopy. For the optimal employment of IEM in the localization of intracellular molecules, the preparation of ultrathin frozen sections of cells and tissues, followed by single or double immunolabeling of these sections, has proved to be the most generally satisfactory procedure. This technology opens up the study of many problems in cell biology that have hitherto been inaccessible to more conventional approaches. Several examples of the application of this technology are discussed.