Notch1b is required for the maintenance of progenitor division and fate. (A) Schematic of the notch1b-MO knock-down experiment: brains are analyzed 2 and 5 days after electroporation of fluorescein-labeled notch1b-MO or control-MO in pallial ventricular cells. (B,C) Analysis of the proliferation status (anti-MCM5) (blue) of electroporated (fluorescein-positive) (green) RG (anti-GS) (magenta), assessed by immunocytochemistry 5 days after electroporation. Arrows indicate proliferating RG, usually notch1b-MO-negative. (D) Proportion of MCM5-positive, GS-positive cells within the MO-targeted population, 2 days (P=0.05) and 5 days (**P<0.001) after electroporation (n=3 brains for each condition). (E) Schematic of the fate analysis in notch1b-MO knock-down experiments: a BrdU pulse is applied 2 days after electroporation of fluorescein-labeled notch1b-MO or control-MO in pallial ventricular cells. Brains are analyzed immediately or after a 3-day chase. (F,G) Analysis of BrdU labeling (white) in electroporated (fluorescein-positive) (green, arrows) RG (anti-GS) (magenta), assessed by immunocytochemistry after a 3-day chase. Arrows indicate fluorescein-labeled BrdU-positive cells in control-MO (glial cells F) and in notch1b-MO (G). (H) Proportion of BrdU-positive, GS-positive cells within the MO-targeted population, 2 days (P=0.05) and 5 days (**P<0.001) after electroporation (n=3 brains for each condition). (I) Proportion of type I (GS positive, MCM5 negative), type II (GS positive, MCM5 positive), type III (GS negative, MCM5 positive) and non-progenitor cells (GS negative, MCM5 negative) [presumably neurons, which virtually constitute the only non-progenitor cell type generated from the pallial GZ (Chapouton et al., 2010; Rothenaigner et al., 2011)] within the BrdU-positive MO-targeted population 5 days after electroporation (type II, neurons: **P<0.001) (n=3 brains for each condition). Scale bars: 10 μm. Confocal projection images from four optical planes, each 0.5 μm thick.
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