To determine the distribution of 5hmC in brain tissue sections, we performed co-detection of this epigenetic modification with a marker for post-mitotic neurons, NeuN, employing commercial anti-5hmC antibody that specifically interacts with this mark but not with other forms of modified cytosine20, 25. Immunohistochemical analysis of 5hmC and 5caC distributions in the adult brain revealed that whereas the prominent 5hmC staining co-localizes with NeuN positive cells, NeuN-negative glial cells possess lower levels of genomic 5hmC (Figure 1)20.