. "The covalent transfer of a methyl group to C-5 of cytosine that contributes to the epigenetic regulation of embryonic gene expression." . . . "DNA methylation involved in embryo development" . "de novo DNA methylation" . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .