Used to preserve fluorescence in immunofluorescence and histochemistry samples by reducing photobleaching during microscopy. Extends the lifespan of fluorescent signals, allowing clearer imaging over time. Commonly applied in cell and tissue imaging, especially in confocal and epifluorescence microscopy. Helps maintain sample integrity during prolonged observation or storage. Often used with fluorescent dyes and fluorescent proteins like GFP, FITC, and TRITC.