Propidium iodide as a nuclear marker in immunofluorescence. I. Use with tissue and cytoskeleton studies.

Some examples are given of immunofluorescence with tissue sections and microtubular cytoskeletons of cultured cells where the fluorescent dye propidium iodide (PI) has been used as marker of nuclei. The emission wave length of IP is longer than that of fluorescein, making it possible to use several different and commonly available filter combinations. The use of nuclei as positional indicators is often a more suitable method than phase microscopy combined with immunofluorescence because of low background illumination against which morphology is viewed, circumventing the need for often expensive phase optics.