Orc51/+ stage 13 egg chambers show a slight reduction in the intensity of BrdU-labelled foci in some follicle cells compared to wild type.
Lethality occurs mostly at the 3rd larval instar stage. BrdU incorporation in third larval instar brains is reduced in homozygotes compared to heterozygotes. Chromosomes are abnormally condensed. Cells are arrested in a metaphase-like state with chromosome congression and spindle defects. There are two types of spindle defects based on severity; in 55% of cases (Class I), most chromosomes appear to congress at the metaphase as a highly condensed chromosome mass, the mitotic spindle is unfocused and spindle fibres are wound about the chromatid mass, and sometimes uneven spindle poles are seen. In 45% of cases (Class II), chromosomes do not congress at the metaphase plate and instead chromatids are seen throughout the spindle and at the spindle poles. In addition, the spindle appears to be diffuse but more focused than Class I. In some cases the spindles are monoastral.