The organization of the actin cytoskeleton in an early Drosophila melanogaster embryo (cycles 9-12) syncytium can be observed by time lapse imaging of embryos expressing a GFP-tagged actin binding protein, moesin. GFP-moesin illuminates actin caps, which form around each centrosome and are located above each nucleus in interphase and prophase. In prophase, pseudocleavage furrows start to ingress from the caps around each nucleus and the forming spindle, which prevents the fusion of adjacent spindles. A description of the capping arrangement can be found in Postner et al., (1992), J Cell Biol., 119:1205. Time lapse 4D spinning disk confocal microscopy images were acquired every 8 seconds and are played at 6 frames/second. The images were acquired with a Nikon microscope (a X40 objective) and a Perkin-Elmer laser spinning disk. The program used to capture, pseudocolor, and process the images was Metamorph.