Almost all embryos derived from females expressing CycB^{CBTPM.Scer\UAS.P\T.T:Avic\GFP} under the control of Scer\GAL4^{nos.UTR.T:Hsim\VP16} arrest in the first mitotic division. In addition to this mitotic arrest, only 38% of eggs derived from females expressing CycB^{CBTPM.Scer\UAS.P\T.T:Avic\GFP} under the control of Scer\GAL4^{nos.UTR.T:Hsim\VP16} appear to complete female meiosis. 50% of the eggs contain multiple small spindles in the dorsal anterior, possibly as a result of meiotic spindle breakdown and/or chromosome mis-segregation. The remaining 14% appear to arrest in meiosis; 4% have two spindles with either one or two X-chromosome signals, indicating arrest in either metaphase or anaphase of meiosis II, while 10% contain a single spindle at the dorsal anterior, typically with two X-chromosome signals, indicating a meiosis I arrest.

When CycB^{CBTPM.Scer\UAS.P\T.T:Avic\GFP} is expressed in syncytial embryos, the vast majority of embryos fail to develop significantly and arrest in mitosis during the early syncytial divisions with their spindles in an anaphase-like state. In the small numbers of embryos that do develop, the CycB^{CBTPM.Scer\UAS.P\T.T:Avic\GFP} protein is not detectably degraded and remains concentrated on centrosomes and spindles throughout the exit from mitosis. When CycB^{CBTPM.Scer\UAS.P\T.T:Avic\GFP} is expressed in cellularized embryos, no mitotic arrest occurs, and CycB^{CBTPM.Scer\UAS.P\T.T:Avic\GFP} protein is completely degraded at the end of mitosis. However, the kinetics of degradation are not normal and the spindle remnants still contain CycB^{CBTPM.Scer\UAS.P\T.T:Avic\GFP} even after mitosis is finished.

When CycB^{CBTPM.Scer\UAS.P\T.T:Avic\GFP} is driven by Scer\GAL4^{mat.αTub67C.T:Hsim\VP16} in the early embryo, spindles are blocked in anaphase.