Table 1.

Comparison of epigenetic reprogramming in mouse zygote and in the developing germline.

zygotic reprogramming	germline reprogramming
active DNA demethylation (paternal genome) linked to the activation of BER	active DNA demethylation linked to the activation of BER
maintenance of genomic imprints	erasure of genomic imprints
lack of ability to re-activate the Xi (SCNT experiments)	re-activation of inactive X chromosome (Xi) in female embryos
maintenance of polycomb histone modifications (H3K27me3)	loss of polycomb histone modifications (H3K27me3)
presence of key pluripotency factors (Oct4, Sox2, Nanog missing)	presence of key pluripotency factors (Oct4, Sox2 and Nanog)