Cryosections were washed with PBS to remove excess OCT and blocked in 10% goat serum (NGS), 0.3% Triton X-100 diluted in PBS for 1 hr at room temperature. The sections were then incubated overnight at 4°C with primary antibodies diluted in PBS containing 10% GS and 0.3% Triton X-100. PBS was used to wash off the primary antibodies and the cryosections were incubated with secondary antibodies in PBS with 10% NGS and 0.3% Triton X–100 for 1 hr. The following primary antibodies were used for immunohistochemistry: anti–NKX2.1 (rabbit, 1:200; Santa Cruz: sc-13040), anti–MAP2 (guinea pig, 1:1,000; Synaptic Systems: 188004), anti–GABA (rabbit, 1:1,000; Sigma: A2052), anti–GAD67 (mouse, 1:1,000; Millipore: MAB5406), anti–SST (rat, 1:200; Millipore: MAB354), anti–CR (rabbit, 1:1,000; Swant: CR7697), anti–CB (rabbit, 1:1,000; Swant: CB38), anti–PV (rabbit, 1:6,000; Swant: PV27), anti–PV (mouse 1:1,000; Millipore: MAB1572), anti–GFP (chicken, 1:1,500; GeneTex: GTX13970), anti–DCX (guinea pig, 1:1,000; Millipore: AB2253); anti–TBR1 (rabbit, 1:200; Abcam: AB31940), anti–GFAP (rabbit, 1:1,000; DAKO Z0334), anti–CTIP2 (rat, 1:300; Abcam: AB18465), anti–OCT4 (rabbit, 1:200, Cell Signaling Technology), anti–SSEA4 (mouse, 1:200, Cell Signaling Technology). AlexaFluo Dyes (Life Technologies) were used at 1:1000
