Propidium iodide is used for detecting dead cells in a given population. The dye can be used to stain both cells and nucleic acids. PI can be used as a DNA stain in flow cytometry to evaluate cell viability or DNA content in cell cycle analysis. The dye also helps to differentiate between apoptotic and necrotic cell death, by being used in conjunction with Annexin V, which stains only apoptotic cells. Additionally, PI can be used in microscopy to visualize the nucleus and different DNA-containing organelles. In plants, PI can visualize the cell wall regardless of cell viability.