Meiotic cells in the testes of heterozygous males show disrupted formation of astral and spindle microtubules.

Spermatid differentiation is defective in males; the organisation of axonemes in the developing sperm tails is disrupted and the doublet tubules appear abnormal. There are also severe meiotic abnormalities, including the formation of multipolar spindles at the second meiotic division in heterozygotes, and the complete failure to form a spindle in homozygotes.

Homozygous females are fertile, homozygous and heterozygous males are sterile. Meiosis is abnormal in the testes of homozygous males; bipolar spindles do not form and the nuclei become misshapen. Chromosome behaviour in prophase appears normal. Metaphase and anaphase configurations are not seen. Cysts at the round spermatid stage show a variety of defects. Cells contain either 4N nuclei or multiple micro- and macronuclei, and multiple mitochondrial aggregates. Meiosis I appears nearly normal in the testes of heterozygous males, although there is a high rate of non-disjunction. Normal meiosis II is not seen in these flies. Cells having tri- and tetra-polar spindles are seen in 16-cell cysts. Chromosome movement in these cells is directed towards the poles, but the chromosomes can move to any or all of the poles. Cysts at the round spermatid stage contain only sixteen cells, have numerous micro- and macronuclei, and have abnormally large mitochondrial aggregates. No mature motile spermatozoa are seen.