Flies homozygous for rod^Z3 are viable and appear normal. However, they are completely sterile; the females lay eggs that fail to hatch. Examination of 3-5-hour-old embryos reveal a number of early developmental defects. None of the mutant embryos reach gastrulation and most present highly abnormal distribution of blastoderm nuclei and unusually large internal nuclei, suggesting problems with syncitial mitoses. In contrast, nearly all wild-type embryos at this stage either begin gastrulation or are in the process of cellularisation.

In 0-2 hour-old syncytial stage rod^Z3-derived embryos, the spacing of nuclei is frequently uneven, and the nuclei cycle asynchronously. The majority of mitotic figures in the mutant embryos are abnormal. The abnormalities include multipolar spindles with multiple centrosomes and poorly focused spindles lacking on or both centrosomes.

In nearly all the eggs derived from rod^Z3 females, the polar body forms a large distinct mass of interphase-like decondensed chromatin instead of the star-burst configuration of condensed chromosomes found in wild-type embryos. The increased size of these polar bodies and the intensity of their DNA stain compared with wild-type suggest that they have an increase in DNA content, presumably owing to additional rounds of DNA replication.

Unlike wild-type controls, rod^Z3-derived syncitial-stage embryos fail to undergo mitotic arrest in response to spindle damage induced by colchicine-treatment.

Examination of the karyotypes of mitotic cells in third-instar rod^Z3 larval brains reveal relatively little aneuploidy. Live imaging of dividing rod^Z3 neuroblasts, however, shows that there is an elevated frequency of anaphases in which some kinetochores migrate poleward more slowly than the others.

RZZ streaming is substantially reduced in both homo- and heterozygous rod^Z3 mutant neuroblasts relative to wild-type.