Measurement of section thickness in quantitative microscopy with special reference to enzyme histochemistry.

Quantitative histochemical techniques demand constancy in sectioning tissue and preferably knowledge of the true thickness of a section. In this investigation a simple, rapid, accurate, and reproducible technique is described for measuring section thickness using an instrument known as a Surfometer. It has been shown that: (a) cryostat microtome settings bear little relationship to the true section thickness of the sections produced; (b) that different instruments differ in their inaccuracies; (c) that this inaccuracy varies slightly with different tissues.If densitometric methods are used and either the absolute amount of a tissue component is to be measured or the amount of a tissue component is to be compared in two tissues then it is mandatory to determine the actual thickness of the section. The method described here seems the most appropriate one for these investigations.