Co-expression of Cdc42^NIG.1253OR and Dcr-2^Scer\UAS.cDa under the control of Scer\GAL4^A3.eya results in a male-sterile phenotype, characterised by spermatogenic arrest at the elongated cyst stage and empty seminal vesicles.

The microfilaments and nuclei of late-stage spermatid cysts show significant structural alterations when Cdc42^NIG.1253OR is co-expressed with Dcr-2^Scer\UAS.cDa under the control of Scer\GAL4^T155. There is a consistent failure to achieve the intertwined and tightly packed organisation of head cyst cell F-actin arrays and associated spermatid nuclei. The microfilament arrays appear sparse and misshapen, and the normally tight and uniformly oriented bundles of nuclei are loosely packed and partially split.