A Simplified Silver Impregnation of Neural End-Feet in Paraffin Sections

Abstract

A simple and rapid method is described for the staining of neural end-feet in the central nervous system. In this technique, paraffin sections of routinely fixed central nervous tissue are dewaxed and mordanted in 10% potassium dichromate at 58d`C for 1–2 hr, and impregnated for 45 min at 58d`C in a 2% silver nitrate solution. Staining takes place in a silver-gelatin reducer; the sections may be gold toned if necessary. By adding 2% chromium fluoride to the chroming solution, it is possible to stain the mitochondria. By completely omitting the mordanting step, a general impregnation of neurofibrils is obtained. Since the cells and their nuclei are not impregnated by this method, sections may be counterstained by any basic anilin dye to bring out the Nissl bodies. A 1% toluidine blue solution buffered at pH 3.0 was found very satisfactory in this respect. This technique has been successfully applied to all parts of the central nervous system including the cerebral cortex.