A method for quantifying electron staining, obtaining the dry specific gravity of specimens in sections, and measuring section thickness

SUMMARY Methods are described for the estimation of the dry specific gravities (SG) of specimens in thin sections, especially for the comparison of one group with another and for the quantification of electron stains. Variations in section thickness are overcome by using the naked supporting film as a base‐line, and relating the SG of the specimen to that of the resin, which acts as a standard. Section thicknesses may also be estimated by using similar methods. The optical densities of their images are compared with those of standards; knowledge of the SG of the resin allows one to calculate its thickness.