PathoGreen™ Histofluorescent Stain is an anionic green fluorescent dye (Ex/Em 497/520 nm) functionally similar to Fluoro-Jade^® dyes. These dyes stain degenerating neurons and their processes after exposure to a variety of neurotoxic insults in brain sections and cultured neurons. The mechanism of neuronal staining by anionic fluorescent dyes has not been determined. It has been proposed that the negatively charged dyes bind to positively charged polyamines or other molecules specifically generated in dying neurons.