(A) Antibody staining for GFAP among SVZ cells, GEPCOTs, and pre-GEPCOTs (scale bar = 5 μm) (n = 3 mice from three independent experiments). (B) The frequencies of neurospheres >50 μm, multipotent neurospheres, adherent colonies, and multipotent adherent colonies (4–6 independent experiments each) formed by unfractionated live SVZ cells, GEPCOTs, and pre-GEPCOTs. (C) Frequency of BrdU+ SVZ cells or pre-GEPCOT cells after BrdU pulses in vivo (n = 5–11 mice/time point in 2–3 independent experiments; note that SVZ data are from Figure 1D for comparison purposes but were obtained in the same experiments). (D–H) Conditional reporter expression in pre-GEPCOT cells at varying times after recombination with the indicated Cre alleles. These data are from the same fate-mapping experiments as shown in Figures 2 and 3, including the same SVZ data for comparison purposes. Cre alleles that only transiently contributed to the SVZ (Dlx1CreERT2 and Ascl1CreERT2) did not recombine in pre-GEPCOT cells, while Cre alleles that gave enduring contributions to the SVZ (Gli1CreERT2, Slc1a3-CreERT, and Sox2CreERT2) did recombine in pre-GEPCOT cells. (I–J) The frequencies and numbers of labeled pre-GEPCOT cells, GEPCOT cells, neuroblasts, and other SVZ cells at varying times after recombination by GFAP-CreERT2 (n = 3–5 mice/time point in four independent experiments). (K) Markers that distinguish pre-GEPCOT from GEPCOT cells. (L–M) Whole-mount SVZs were stained with anti-acetylated tubulin (red), anti-β-catenin (blue), and either anti-GFAP (L, green) or anti-EGFR (M, green) antibodies and pinwheel structures were inspected for the presence of GFAPhigh pre-GEPCOT cells (open arrow in L and M) and EGFRhigh GEPCOT cells (hatched arrow in M) by confocal microscopy. Images were taken at the apical surface except the GFAP depth projection which is a composite of 11 images at 2 μm intervals into the tissue. Scale bar = 5 μm. All data represent mean ± SD. Statistical significance of differences between SVZ and pre-GEPCOT cells in C was assessed with two-tailed student's t tests. Statistical significance of differences in D–J (among time points) was tested with a one-way ANOVA followed by Tukey's post-hoc tests for multiple comparisons. *p<0.05, **p<0.01, ***p<0.001, n.s. not significant.