Fig. 2.

Contrast formation in micrographs of unstained frozen-hydrated vitrified sections. (A) Schematic view of a section containing an SV (*), a cross-sectioned microtubule (Mt), a membrane aligned in the viewing direction, and two membranes tilted by 10° and 30°, respectively. The section thickness is 70 nm. (B) Optical density expected from a micrograph of the above section.