Histochemical methods for proteins in tissues submitted to decalcification. A histophotometric study

4 histochemical methods for demonstration of protein acid groups: Nihydrin-Schiff, Millon, DDD and DMAB-nitrite were applied in sections of rat pancreas fixed in the following fixatives: 10% formalin, 10% formalin in saline, ZENKER and GENDRE, and treated with the following decalcifying solutions: 5% nitric acid, 5% trichloroacetic acid, 33% formic acid, 5% EDTA pH=7.0 JENKINS, GREEP and citrate buffer pH=4.5. The colour intensity of each reaction was measured photometrically over the zymogen granules region of the acinar cells, using a Zeiss histophotometer, and compared with controls, i.e., fixed tissue which have not been treated with decalcifying solutions. The results have shown that for each method there is more than one combination fixative-decalcifying solution which gives results similar to those of the control.