Histochemical Specific Demonstration of the Carboxyl Group in Tissue Sections

Abstract

The authors devised a method of histochemical demonstration of carboxyl groups in tissue sections. This method is dependent upon the principle of specific formation of acid chloride from the carboxyl group through the action of thionyl chloride in the first step of the method. Newly formed acid chloride was converted into acid amide in a dilute ammonia solution in the second step. The acid amide was precipitated as a metaphosphate in a concentrated sod. metaphosphate solution in the third step. Thereafter, metaphosphate was converted into silver salt in a silver nitrate solution. The silver salt was reduced to metallic silver by the neutral formol solution. The metallic silver was replaced by metallic gold by immersing in a gold chloride solution to inprove observation under a microscope. There were some problems encountered in this method which are described in the item of comment of this report. Further investigations will be performed by the authors.