The d16/d14 ratio of sphingolipids in both third instar larvae and adult testes is affected in mutant animals, with an elevation of d16-containing sphingolipids compared to wild type.

A large proportion of fro^Z0287 mutant spermatids have one large nebenkern with four nuclei of normal size, indicating a cytokinetic failure in both meiotic divisions. A smaller proportion have two nuclei and a large nebenkern, indicating failure of only one of the meiotic divisions. A small proportion (<6%) of fro^Z0287 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, a significant amount (>7%) of spermatids have more than four nuclei, which may result from defects in the mitotic divisions preceding mitosis. During early telophase of fro^Z0287 spermatocytes, there is an actin ring of normal appearance and and a normal central spindle. However, as telophase progresses the actin ring fails to fully constrict. In some late telophase figures, the central spindle either becomes less dense or completely disorganized, while in others the central spindle is not affected. The cleavage furrow initiates ~10 minutes after anaphase onset as in wild type, but shows a limited ingression and then regresses leading to a failure of cytokinesis.