Widely used in fluorescence microscopy and flow cytometry to stain DNA in fixed cells. This chemical readily penetrates cell membranes and binds to the minor groove of double-stranded DNA, emitting bright blue fluorescence when excited by UV or violet light. It is ideal for nuclear counterstaining, allowing clear visualization of cell nuclei in multicolor fluorescent labeling experiments. Commonly used in combination with green or red fluorescent probes to distinguish cellular structures and assess nuclear morphology. Also applied in cell cycle analysis and apoptosis detection due to consistent staining intensity proportional to DNA content. Its compatibility with various fixation methods and other fluorescent dyes makes it a standard tool in cell biology and histology.