A Controllable Silver Stain for Nerve Fibers and Nerve Endings

Abstract

A paraffin section method is described with a yellow-brown-black color range comparable to that of Ranson's pyridine silver block stain. After impregnation with activated protargol and reduction with a fine grain photographic developer, silver nitrate impregnation and reduction are repeated as often as necessary. The procedure is as follows: Place hydrated sections of tissue fixed in chloral hydrate (25 g. in 100 ml. of 50% alcohol) in 1% aqueous protargol (Winthrop Chemical Co.) containing 5-6 g. metallic copper for 12-24 hours. After rinsing in 2 changes of distilled water, reduce 5 to 10 minutes in: Elon (Eastman Kodak Co.) 0.2 g., Na₂SO₃, dessicated, 10 g., hydroquinone 0.5 g., sodium borate powder 0.1 g., distilled water 100 ml. Wash thoroly in 4 or 5 changes of distilled water and place in 1% aqueous AgNO₃ for 10-20 minutes at 28°-50° C. Rinse in 2 or 3 changes of distilled water and reduce in the elon-hydroquinone solution. After thoroly washing in 4 or 5 changes of distilled water, examine under microscope. If too pale, treat again in silver nitrate for 10-20 minutes, rinse, reduce 5-10 minutes and wash thoroly until nerve fibers show distinct microscopic differentiation, then dehydrate, clear and mount.