QUANTITATIVE TESTS OF HISTOCHEMICAL METHODS FOR PHOSPHOMONOESTERASES IN BRAIN TISSUE

Abstract

Reliability of quantitative simultaneous coupling azo dye-based histochemical methods for acid and alkaline phosphatase activity was tested by comparing them with biochemical assays of tissue homogenates for the same activity using a modification of Gomori's phenol method. Gradations of histochemical staining observed with those methods, under carefully standardized conditions, reflected accurately enzyme levels obtained by assays of homogenized tissue. Stability of dyes formed by the histochemical reaction and the optimal method of extraction were investigated. Both nonspecific absorption and lipid solubility of reaction product could be excluded as possible sources of artefacts. The influence of section thickness, number, and storage, volume of medium, incubation time, and formalin fixation on activity measurements was studied.