Electron tomography is the most winery applicable method for obtaining thre
e-dimensional information by electron microscopy. It is, in fact, the only
method suitable for investigating pleomorphic structures, such as many supr
amolecular assemblies, organelles and cells. With the recent development of
automated low-dose data-acquisition schemes, it is now possible to study m
olecules and cells embedded in vitreous ice. This opens up new horizons for
investigating the functional organization of cellular components with mini
mal perturbation of the cellular context.