Cryo field emission scanning electron microscopy.

Low-temperature scanning electron microscopy (cryoSEM) was introduced in the early 1970s, shortly after the appearance of the first commercial scanning electron microscopes. This technique has been utilized widely in plant biology, the food and paper industry, X-ray analytical studies, and material sciences (8). Major advantages of cryoSEM include being able to avoid deleterious changes associated with preparative steps that remove water and produce extraction/shrinkage of tissue. CryoSEM can provide convenience and speed of sample preparation but has been considered to be a medium-resolution technique (50–100 nm). With the advent of field emission SEM (FESEM) and new developments in cryo-preservation of biological specimens, it has now become possible to achieve resolution in the macromolecular (2–3 nm) range.