Incubate the tissue sections in 100 µl of a 1:5,000 dilution of mouse monoclonal anti-5hmC and a 1:1,000 dilution of rabbit polyclonal anti-5caC primary antibodies in blocking solution for 1 hr at RT in a humid chamber. Alternatively, perform the incubation overnight at 4 °C if needed. NOTE: Sections processed without primary antibodies can serve as suitable negative controls for the staining procedure. The 12.5 days post coitum murine embryonic brain sections enriched in 5caC, 5fC and 5hmC 20 can be used as positive control.