图2.Macrophages cultured on a polymer surface that have fused to form a foreign-body giant cell following treatment with interleukin-4.Macrophages cultured on a polymer surface that have fused to form a foreign-body giant cell following treatment with interleukin-4. Cells were fixed with 3.7% formaldehyde, treated with RNase A and stained with rhodamine phalloidin (Cat. no. R415) to visualize F-actin, and with YO-PRO®-1 iodide (Cat. no. Y3603) to visualize cell nuclei. Cells were imaged with a Bio-Rad MRC600 confocal laser-scanning microscope. The image is a composite of optical sections taken through the Z-axis of the cell. F-actin (red) is restricted to the periphery of the multinucleated cell and surrounds a cluster of nuclei (green). Image contributed by Kristin DeFife and James M. Anderson, Institute of Pathology, Case Western Reserve University.