Embryos produced by cnn^mfs7/Df(2R)cnn; cnn^ΔEx1A females exhibit multiple nuclei and spindles scattered throughout the embryo (deep and cortical) and frequent nuclear fusions. These embryos produce normal triploid polar bodies following the completion of meiosis. In the mutant embryos, early spindles frequently have an obvious spindle pole, but the poles are lost as development proceeds and barrel-shaped anastral spindles accumulate, accompanied by nuclear fusions.

The number of adults that develop to adulthood represents only 0.5% of eggs laid by cnn^mfs7 mutant females that also express cnn^{PA.Scer\UAS.P\T.T:Avic\GFP} under the control of Scer\GAL4^{nos.UTR.T:Hsim\VP16}.

The failure of embryogenesis in mutant animals is associated with the appearance of multiple metaphase spindles fused at a common pole.

Homozygous females produce embryos that arrest prior to cellularisation. Embryos derived from cnn^mfs7/Df(2R)cnn females have severe defects in nuclear division and distribution. Defective divisions, as indicated by chromosomal bridges and giant nuclei, are evident very early during the syncytial divisions. Normal divisions usually outnumber abnormal divisions during cycles 1-5, but by cycle 8 and the cortical migration stage the embryos have accumulated a large number of defective nuclei that are grossly polyploid. These nuclei form large masses of chromosomal aggregates in the interior of the embryo, leaving large areas of the cortex devoid of nuclei. The nuclei that do migrate to the surface are not uniform in their cell cycle states. Many spindles are morphologically normal before cortical migration. After this stage, the spindles are not evenly distributed in at the cortex. Shared spindle poles are seen, resulting in trains and rosettes of linked spindles. Large barrel-shaped spindles, monopolar and multipolar spindles and spindles with larger than normal complements of DNA are also seen. The embryos never achieve cellularisation.