Immunohistochemistry

Immunohistochemistry was performed on 12 μm cryostat sections on slides, or 30–50 μm free floating sections (Ma et al. 2013; Zhang et al. 2016). For Sp9 immunohistochemistry, sections were boiled in 10 mM sodium citrate briefly for antigen retrieval. BrdU labeled sections were incubated in 2 N HCl for 1 h at room temperature, and then rinsed in 0.1 M borate buffer twice. The following primary antibodies were used: goat anti-Sp8 (1:1000, Santa Cruz, sc-104 661), rabbit anti-Sp9 (1:500) (Zhang et al. 2016), rabbit anti-CR (1:2000, Swant, 7699/3H), mouse anti-CR (1:1000, Swant, 6B3), rabbit anti-PV (1:3000, Swant,PV25), mouse anti-PV (1/1000, Sigma, P3088), rabbit anti-CB (1:10 000, Swant,CB38), mouse anti-CB (1:10 000, Swant, 300), mouse anti-TH (tyrosine hydroxylase, 1:400, Millipore, MAB318), chicken anti-GFP (1:3000, Aves Labs, GFP-1020), goat anti-DCX (1:1000, Santa Cruz, sc-8066), mouse anti-PSA-NCAM (1:1000, Millipore, MAB5324), mouse anti-NeuN (1:500, Millipore, MAB-377), rat anti-BrdU (1:50, Accurate Chemical, OBT0030s), rabbit anti-Ascl1 (1:2000, Cosmo Bio, SK-T01-003), rabbit anti-Gsx2 (1:2000, Millipore, ABN162), and rabbit anti-cleaved Caspase-3 (1:500, Cell Signaling, 9661L).