Histofluorescence in the unperfused CNS by cryostat and glyoxylic acid: a preliminary report

This paper describes an adaptation of glyoxylic acid histofluorescence to cryostat sections. The technique utilizes unperfused frozen brain, cryostat sectioning, immersion in 2% glyoxylic acid solution, warm-air drying, and exposure to hot glyoxylic acid gas. Fine, well-localized catecholamine histofluorescence is produced in cells, axons, and terminals. Both the anatomical localization and pharmacological specificity of the fluorescence conform to traditional catecholamine literature. The technique has the advantage of overcoming preservation and sectioning problems associated with the Vibratome. Because unperfused brain is used, alternate sections can be prepared for a variety of anatomical demonstrations or biochemical assays.