Silverman L, Schreiner B, Glick D
J Cell Biol. 1969 Mar;40(3):768-72. doi: 10.1083/jcb.40.3.768.
To apply the method of quantitative electron microscopy to the measurement of mass in thin sections, the thickness of the section at or very near the structure to be studied must be known. Dowex anion exchange resin AG 1 x 2, stained with phosphotungstic acid (PTA) at pH 6.4, was used as a thickness standard which could be embedded and sectioned. The sectioned PTA-Dowex appeared uniformly stained and exhibited suitable electron opacity. The stoichiometry of the reaction between PTA and the Dowex resin was measured by three independent methods based on gravimetric, colorimetric, and nitrogen determinations whose results showed close agreement. From the PTA uptake, the density of the stained spheres was calculated. Mass of a defined area of PTA-Dowex was measured by quantitative electron microscopy, and from this mass and density, the volume and then the thickness were calculated. The values for thickness were compared to those obtained by interference microscopy on the embedding medium alone in the same sections.
为了将定量电子显微镜方法应用于薄切片中物质的测量，必须知道待研究结构处或其附近切片的厚度。用磷酸钨（PTA）在pH 6.4条件下染色的Dowex阴离子交换树脂AG 1 x 2被用作可包埋和切片的厚度标准。切片后的PTA - Dowex呈现均匀染色且具有合适的电子不透明度。基于重量法、比色法和氮测定法的三种独立方法测量了PTA与Dowex树脂之间反应的化学计量，其结果显示出密切的一致性。根据PTA的摄取量，计算出染色球体的密度。通过定量电子显微镜测量PTA - Dowex特定区域的质量，并根据该质量和密度计算出体积，进而计算出厚度。将厚度值与通过干涉显微镜仅在同一切片中的包埋介质上获得的值进行比较。
