(A–A′, C–C′) Wild-type type II NB lineages in a third instar larval brain. mCD8-GFP driven by pntP1-GAL4 labels all type II NB lineages (A–A′) or a single type II NB clone (C–C′). Ase− immature INPs, Ase+ immature INPs, and mature INPs are indicated by open arrows, solid arrows, and arrowheads, respectively. (B–B′, D–F′) Btd RNAi knockdown type II NB lineages (B–B′) or type II NB clones homozygous mutant for btdXG81 (D–E′) or btdXA (F–F′) in 3rd instar larval brains produce Ase− immature INPs (open arrows) and a few Ase+ daughter cells (arrows) but no mature INPs. Only 3 out of total 8 type II NB lineages are shown in (A–A′) and (B–B′). In this and all other figures, asterisks indicate type II NBs and scale bars equal to 20 µm. Dpn staining alone shows the NB and mature INPs. (G–H) Quantifications of the number of mature INPs (G) and the percentage of type II NB lineages with mature INPs (H) in the wild type, Btd RNAi knockdown, and btd mutant type II NB lineages. The numbers on top of each bar are the numbers of type II NB lineages analyzed except for the numbers for the wt and btd RNAi in (H), which are the number of brain lobes examined. The mean and stdev for btdXG81 and btdXA in (H) are calculated by bootstrapping. **p < 0.01, *p < 0.05 (Student t test).