Following a method described elsewhere [18 (link)], doublecortin (DCX) immunohistochemistry was performed. After the sections were incubated in 3% H2O2 for 30 minutes at room temperature, they were blocked by 10% normal rabbit serum in PBS with 0.2% Triton X-100 and 1% bovine serum albumin for 1 hour. The section was incubated in goat anti-DCX antibody (1:500; Santa Cruz Biotechnology, Santa Cruz, CA, USA) at 4℃ overnight. After washing 3 times, the sections were treated with a biotinylated goat secondary antibody (1:200; Vector Laboratories) for 1 hour, followed by another hour with avidin–peroxidase complex (1:100; Vector Laboratories). The sections were visualized in 50mM Tris-HCl (pH, 7.6) containing 0.03% hydrogen peroxide and 0.03% DAB for immunostaining. The slides were dehydrated by alcohol and mounted using Permount coverslips (Thermo Fisher Scientific Inc.).