TEM: A precious evergreen approach to cell biology and pathology

In this work the role of transmission electron microscopy (TEM) in biology and pathology studies is emphasyzed. A overview on technical procedures is provided and their advantages or disadvantages, with particular attention to possible artifacts, are reported. The importance of the ultrastructural approach in cell and isolated organelle characterization, frequently correlated to functional and molecular analyses, is supported by specific images and by a cospicous number of references. Negative staining, a simple and rapid method, is also described and a number of examples from different types of viruses are illustrated. Cryo-EM is finally mentioned. It is illustrated by means of frozen ultrathin sections, compared to those from epon embedded conventional ones. Finally, freeze-fractured sample replicas are presented, both aimed at membrane detail highlighting and inner cell structure investigation. TEM, in its variety of applications, and in particular if integrated by molecular studies, is a very important tool in the study of life sciences and, in general for nanotechnology.