RETHINKING CELL STRUCTURE

Cell structure, emerging from behind the veil of conventional electron microscopy, appears far more complex than formerly realized. The stan dard plastic-embedded, ultrathin section can image only what is on the section surface and masks the elaborate networks of the cytoplasm and nucleus. Embedment-free electron microscopy gives clear, high-contras t micrographs of cell structure when combined with removal of obscurin g material such as soluble proteins. The resinless ultrathin section i s the technique of choice; it is simple and inexpensive, and it uses o rdinary electron microscopes. The resulting pictures reveal a world of complex cell structure and function. These images necessarily change our conception of the cytoskeleton, nuclear matrix, mitosis, and the r elation of membranes to cytostructure.