Two useful techniques in three-dimensional electron microscopy: quarter-micron serial sectioning and stereoscopy.

Quarter-micron serial sectioning is a technique useful for 3-D analyses in which light microscopical resolution is not sufficient and the maximal resolution of the electron microscope is not necessary. We propose that the technique described here is advantageous for many current electron microscopic studies in which ultrathin sections are commonly used. In particular, the sections are sturdier; they yield high-contrast images; they contain, per section, more information about the third dimension, information that can be retrieved through stereoscopy; and, when it comes to 3-D reconstruction from serial sections, less sections are needed to reconstruct tissue elements contained in a bloc of a given size. Compared to thicker sections, quarter-micron sections yield images of acceptable readability.