Deparaffinized brain sections were immersed in EDTA (pH 8.0) and heated in the microwave for antigen retrieval. After three washes with phosphate-buffered saline (PBS; pH 7.4), an autofluorescence quencher (Servicebio; cat. no. G1221) was added to the sections, followed by incubation for 30 min in blocking solution containing bovine serum albumin (BSA; Servicebio; cat. no. G5001). The sections were incubated overnight at 4°C with rabbit primary antibodies against GFAP and Olig2 (both used at 1:100). To detect incorporated BrdU, two extra steps were performed—i.e., DNA denaturation (1 mM HCl at 37°C) for 30 min and HCl neutralization (50 mM sodium borate buffer, pH 8.5) for 20 min. The sections were incubated overnight with a mouse primary antibody against BrdU (1:100), washed three times with PBS, and incubated with Cy3-conjugated anti-rabbit (1:300, Servicebio; cat. no. GB21302) and AlexaFluor488-conjugated anti-mouse (1:400, Servicebio; cat. no. GB25301) secondary antibodies for 50 min in the dark. Finally, the sections were stained with DAPI (Servicebio; cat. no. G1012) for 10 min, washed three times, and sealed with fluorescent mounting medium (Servicebio; cat. no. G1401). Fluorescent signals were visualized with an epifluorescence microscope (Eclipse C1; Nikon) at 40× objective and signals in three areas of the corpus callosum were quantified with an imaging system (DS-U3; Nikon). Double-positive cells were manually counted in five sections from each animal with Image-Pro Plus v6.0 software by a blinded investigator.