Fig. 7. In mouse, Trk signaling in embryonic precursors is necessary for maintenance of normal numbers of precursors in the postnatal SVZ, but not for astrocyte formation. Cortices were electroporated with EGFP and the empty vector (control), dnTrkB, dnTrkC or both (dnTrkB/C), and analyzed at P3. (A) Confocal micrographs of coronal sections through the electroporated VZ/SVZ immunostained for EGFP (GFP, green) and GFAP (red). The right panels show the merges. Arrows indicate double-labeled cells. (B,C) Quantification of micrographs similar to those in A for the percentage of (B) EGFP-positive cells and (C) EGFP, GFAP-positive cells in the VZ/SVZ. n=five, five sections/cortex. (D) Quantification of confocal micrographs similar to A where cortices were co-electroporated with EGFP and control shRNA (control) or TrkB shRNA (shTrkB) to determine the percentage of EGFP, GFAP-positive cells within the VZ/SVZ. n=four control and three TrkB shRNA brains. Error bars indicate s.e.m. Scale bar: 100 µm. ^**P<0.01; ^***P<0.001 relative to control-transfected sections.