Semipermeable membranes for improving the histochemical demonstration of enzyme activities in tissue sections

Summary An improved histochemical technique for the demonstration of acid phosphatase in tissue sections is described. With this technique a semipermeable membrane is interposed between the incubating solution and the tissue sections preventing diffusion of enzyme into the medium during incubation. Moreover fixation of the tissue sections in order to minimize enzyme diffusion and that causing a partial inactivation of the enzyme, is no longer necessary. In the histochemical system the enzyme catalyzes the hydrolyzes of naphthol AS-BI phosphoric acid. The enzyme localization is visualized by means of simultaneous coupling of the released naphthol with hexazotized pararosanilin. Problems involved in the histochemical demonstration of the enzyme are discussed.This investigation was in part supported by a grant from the Netherlands Organization for the Advancement of Pure Research (ZWO).The author wishes to acknowledge the valuable technical assistance of Mr. E. D. J. Lindenbergh and Mr. A. H. T. Vloedman.