The average number of apoptotic cells per larval wing disc is increased fourfold in mutant flies compared to wild type.

The wing discs of mus304^unspecified mutant third instar larvae exhibit similar levels of apoptosis to controls in response to X-ray induced irradiation. As in controls, very little apoptosis is seen in the absence of irradiation.

24% of mutant embryos show uniform nuclear morphology and spacing as seen in interphase 14 in wild-type embryos, 16% are arrested at an early stage of embryogenesis, apparently between cycles 3 and 5 and have highly fragmented nuclei, and 60% show a complete or partial arrest at about cycle 14 with severe disruptions in nuclear morphology and spacing. Defects in nuclear divisions are visible during anaphase 12 and become more severe during cycles 13 and 14. Defects include asynchronous and incomplete chromosome segregation as well as fused and irregularly spaced nuclei during interphase. In 3 out of 6 embryos examined, interphase fails to lengthen until cycle 14 and interphase 14 is interrupted by a premature mitosis 14.