How Thin Should a Section Be?

Abstract

The limitations of Ornstein''s conclusions (Jour. Biophys. and Biochem. Cytol., 2, No. 4, Suppl., 53), regarding the maximum useful thickness of a section for electron microscopy, are discussed in the light of earlier experimental and theoretical'' work by the author, which showed that the attainable resolution is of the order of one-tenth the section thickness. At the usual working voltage of 50 to 60 kv and for a resolution of 20 A the maximum thickness should be of order 200 A. Thicker sections will give such a resolution only if embedding material is removed with the electron beam, or if a much-higher voltage is used.