pbl^Z4836/Df(3L)pbl-NR mutant flies display Golgi-derived vesicles that are excluded from the equatorial region of the cell in 96% of telophases.

The majority of pbl^Z4836 mutant spermatids have one large nebenkern with four nuclei of normal size, indicating a cytokinetic failure in both meiotic divisions. A much smaller proportion have two nuclei and a large nebenkern, indicating failure of only one of the meiotic divisions. Occasionally spermatids are seen (<1% of cases) with three nuclei, which may be due to failure of cytokinesis in the first meiotic division, followed by budding off of only one daughter cell in the second meiotic division. The majority of pbl^Z4836/Df(3L)pbl-NR mutants also contain spermatids with four nuclei, and a small proportion contain two nuclei, but the three nuclei phenotype is not seen. Spermatocytes of pbl^Z4836 mutants lack all major equatorial structures that are present in wild type during ana-telophase; there is no organized central spindle, anillin equatorial band or actin ring. This phenotype also occurs in pbl^Z4836/Df(3L)pbl-NR mutants.