This movie is of a Drosophila melanogaster early embryo (cycle 12) expressing GFP-tubulin (green) and injected with Rhodamine-labeled histones (red) and 8mg/ml RanT24N, a dominant negative inhibitor of spindle assembly). In this movie, the relative organization of microtubules (green) and chromosomes (red) can be seen. In early stages, Drosophila embryos divide syncytially. When spindles assemble, chromosomes attach to kinetochore microtubules and then they congress to the metaphase plate and disjoin in anaphase. Next they move to the poles and when they reach the poles in telophase they decondense and two daughter nuclei form. A low dose of RanT24N, a dominant negative mutant of Ran, causes mild defects in spindle assembly and chomosome division. In the middle of the field of view, the assembly of some spindles is inhibited and some form as a circle of microtubules around the chromosomes. At the edge of the field of view, spindles assemble but some microtubules grow away from the spindle. In some cases, nuclei do not divide. In others, chromosomes do not align properly, or lag behind the rest in anaphase. And, in some cases, permanent or resolving bridges occur between the daughter nuclei. 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.