For each immunohistochemical procedure, a series of sections was stained using standard immunohistochemical protocols as previously described [30 (link),31 (link),38 (link)]. Mouse monoclonal anti-5-mC (dilution 1:500, Genway Biotech, San Diego, CA, USA) was used as a primary antibody for 5-mC, and a biotinylated donkey anti-mouse (dilution 1:200; Jackson Westgrove, PA, USA) as the secondary antibody. For the detection of 5-hmC, a rabbit polyclonal anti-5-hmC antiserum (dilution 1:25,000; Active Motif, Rixensart, Belgium) was used as a primary antibody and a biotinylated donkey anti-rabbit (dilution 1:200; Jackson Westgrove, PA, USA) as the secondary antibody. For each primary antibody, the sections were processed as a single batch to avoid differences in staining intensities between batches. The specificity of the commercially available primary antibodies has been confirmed in our previous work [25 (link),39 (link)]