Most vib¹³³ homozygous somatic clones in the larval brain show variable numbers of type I and type II neuroblasts (absent or ectopic), as compared to control clones; the loss of neuroblasts is likely due to premature differentiation (as a high proportion of neuroblasts show nuclear localization of Prospero) rather than apoptosis (as there is no increase in active Caspase 3 staining). These mutant neuroblasts are significantly smaller than in control clones.

vib¹³³/vib^j5A6 transheterozygous larval brain neuroblasts display highly prevalent cytokinesis defects and frequently defective asymmetric cell divisions, as compared to controls: aPKC, Par6, and Gαi, but not Baz, Insc, Pins and Cdc42, fail to localize to a strong apical cortex crescent during metaphase; Mira, Pros, Brat, Numb and Pon fail to localize to a strong basal cortex crescent during metaphase; and the mitotic spindle axis is misoriented with respect to the neuroblast polarity, although centrosomes and spindle architecture are apparently unaffected.