Freeze-fracture transmission electron microscopy

Freeze-fracture electron microscopy is one of the oldest methods of a large family of valuable cryoelectron microscopic techniques, based on initial cryofixation of the specimens. Its main advantage for low- and medium-resolution structural studies is the very large spectrum of different materials (solid, liquid, suspension, etc.) and experimental conditions (composition, temperature, pressure, etc.) that may be used. Most of the corresponding procedures require, nevertheless, a careful evaluation of the effects of cryofixation, fracture and replication upon the sample structure. Among the methods that might be used for such evaluation, X-ray diffraction is the most straightforward. The largest advances in freeze-fracture transmission electron microscopy are, indeed, due to the combined use of X-ray scattering and freeze-fracture, particularly when applied, together with image analysis, to the determination of the structure of three-dimensionally ordered specimens.