A large proportion of cia^Z2269 mutant spermatids have one large nebenkern with four nuclei of normal size, indicating a cytokinetic failure in both meiotic divisions, while a much smaller proportion have two nuclei, indicating failure of only one of the meiotic divisions. A very small proportion (1%) of cia^Z2269 spermatids have 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. Further, occasionally spermatids are seen (4% of cases) with more than four nuclei, which may result from defects in the mitotic divisions preceding mitosis.