Preparation of ultrathin frozen sections in electron microscopy: specimen supported by polyethylene glycol.

A method was worked out for supporting biological specimens with polyethylene glycol (PEG) for the preparation of ultrathin frozen sections. This method was used in the preparation of ultra-thin cryosections of various tissues and of human diploid cell suspensions infected with vaccina and Herpes simplex viruses. In such preparations it was possible to study stages of virus particle formation under the electron microscope.