mil^hanabi-1 homozygous spermatid clusters are lost at earlier stages during spermatogenesis and spermatid nuclei are found scattered along the spermatid cyst, as compared to controls.

Mutant males lack mature sperm in the seminal vesicle. Nuclei are completely scattered in the mutant testes during spermatid elongation (in contrast to the clustering seen in wild type) and actin cones are not observed. Even though the mutant nuclei are not clustered, the individual nuclei appear to elongate towards a thin shape until the canoe stage. At later stages, most of the mutant nuclei are aberrantly small and oval shaped.