Demonstration of cathepsin B in the rat kidney using fluorescence histochemistry

The procedure of mounting freeze-dried sections with celloidin was adapted for the fluorescent-histochemical demonstration of cathepsin B in the rat kidney. A good localization of reaction products was shown in freeze-dried, 5-micron sections which had been mounted free floating with 1.5% celloidin solution on albuminized slides. Using this procedure, the reaction products were localized in the lysosomes, particularly those of the convoluted proximal tubule.