Contrast in unstained sections: a comparison of bright and dark field electron microscopy

Abstract

Resolution in bright field electron micrographs of stained tissue sections is determined primarily by heavy atom clusters required for contrast and visibility of biological structure. Omission of heavy metal stains results in loss of visibility. The use of dark field microscopy on very thin sections is shown to increase the visibility of structure to the degree that heavy atoms can be completely omitted from the preparation. This suggests the use of lighter atom compounds as stains in chemical and cytochemical analyses of tissues, as well as further instrumental developments towards the achievement of higher resolution.