Figure 2.

Kinetics of Genome-wide Demethylation in Early Embryos, PGCs, and ESCs

Impairment of methylation establishment and maintenance contributes to genome-wide demethylation in vivo (early embryo and PGCs) and in culture (naive ESCs), as do the oxidation and base excision repair pathways. Approximate levels of 5-methylcytosine (5mC) and 5-hydroxymethylcytosine (5hmC) are represented by blue and red lines, respectively. Dashed blue lines indicate the expected level of 5mC if demethylation was caused solely by complete inactivation of maintenance methylation.