Staining for Autoradiography of the Central Nervous System

Abstract

Central nervous system (CNS) histological stains have been tested for their compatibility with autoradiography. Both paraffin and frozen sections were used. Frozen sections were mounted on subbed slides, dried overnight, dehydrated, defatted in xylene for 1 hr and then rehydrated. Slides were coated by dipping in Kodak NTB2 emulsion. All Nissl stains except gallocyanin gave good results when used after development. Myelin staining was more difficult because iron alum dissolved silver grains if used after development and Weil, Woelcke, and Weigert prestained sections are bleached by the photographic fixer. Luxol fast blue (LFB) used before coating was judged best for myelin staining of both paraffin and frozen sections. Bodian and Holmes silver stains for axons gave good results when used before coating. Stains requiring iron alum or periodic acid-Schiff (PAS) were not usable on frozen sections due to severe suppression of grain formation in the emulsion. Many stains (Woelcke, lithium hematoxylin-Darrow red, LFB-Nissl stain, LFB-PAS-hemalum) work if iron alum, LFB and PAS steps are done before and the remainder after coating. A quantitative study of the effect of these stains on the grain count of H³-leucine, proline and fucose-labeled CNS tissue shows that most Nissl stains and LFB-stained paraffin sections have counts similar to unstained tissue, while LFB-stained frozen sections show a 20% decrease.