The fraction of mitotic cells in larval brain squashes is increased compared to wild type. There is an increase in the number of prometaphase/metaphase figures. The mitotic cells frequently contain misaligned chromosomes. Chromosomes sometimes appear to be undercondensed. The chromosomes are much less tightly associated with the metaphase plate than in wild-type cells. Many mitotic nuclei have chromosomes that are not correctly aligned on the metaphase plate in embryos derived from homozygous female germline clones. Centrosomes that are no longer associated with nuclei are seen. Numerous polyploid nuclei are present. These defects are seen as early as the 8th embryonic mitosis and become more prominent during later cell cycles. Anaphase defects, such as unequal anaphases lacking centrosomes are also observed in less than 10% of mitoses. Chromosome congression appears to proceed relatively normally in these embryos, but the chromosomes do not stably persist at the metaphase plate. Sporadically, they move off the plate before anaphase onset. Anaphase takes place on schedule, and occurs simultaneously for both aligned and misaligned chromosomes. In no case is premature sister chromatid separation of aligned or misaligned chromosomes seen, and the duration of anaphase is not significantly extended.