Homozygous, tbrd-11/Df(3R)ED10893 and tbrd-11/Df(3R)Exel9014 males are completely sterile.
The Nebenkern is larger than the nucleus in early round spermatids in homozygous males. The nuclei of mutant spermatids remain small and round (in contrast to the elongated shape that develops in wild type). In addition, spermatid nuclei are scattered throughout elongated bundles of flagella instead of being clustered at one end as in wild type. Investment cones are formed in homozygous mutants, but individualisation complexes are never seen.