Fig. 5. Exposure of explants to RA increases neurogenesis in the SVZ-olfactory bulb pathway. (A,B) Explants were treated with vehicle (Veh; A) or RA (10 µM; B) for 4 DIV and then immunostained for calretinin. Note increased calretinin immunoreactivity and thicker RMS (arrows) in the RA-treated explant (B) compared with Veh (A). (C,D) Confocal images of re-sectioned explants (50 µm thick slices) double immuntstained for calretinin (green) and BrdU (red) after a 4-day exposure to Veh (C) or 10 µM RA (D). Explants were incubated with BrdU from 24-48 hours in vitro. Most BrdU-labeled cells in the RMS (arrows) express calretinin; the RMS is expanded in the RA treated slice. Insets in panels C and D show double labeled cells (arrows; BrdU at top; calretinin middle; merged at bottom). OB: olfactory bulb. ^*Denotes the lateral ventricle. Scale bar: 200 µm for A,B; 100 µm for C,D; 40 µm for insets.