Preparation of biological cryosections for analytical electron microscopy

A cooling chain for studies of ultrastructure and elemental composition of cryofixed biological cells and tissues is described. The technique is demonstrated for yeast cells. The preparation steps such as cryofixation, cryosectioning, transfer into the electron microscope as well as imaging and X-ray microanalysis in the STEM are discussed with respect to the present possibilities and problems. Whereas freeze-dried cryosections can be studied routinely, imaging of the ultrastructure and measurement of the elemental distribution in frozen-hydrated sections turn out to be limited.