Activation Of Embryonic Genome Embryonic gene activation is a process by which the embryo begins to transcribe its newly formed genome.As the embryonic gene activation occurs during early stages the paternal genome may not have any influence at that stage. Now, My question is why does only the maternal genome play a role in embryonic gene activation? Does paternal genome have a role in prior/post embryonic genome activation?

The pronuclei fuse and decondensation happens and now the cell is called a zygote. There is a stage called the midblastula transition (MBT), until which only the maternal products (cytoplasmic factors such as RNAs, proteins and ribosomes) are used. After MBT the zygote starts expressing its own genes from both the paternal and maternal alleles. However, certain genomic regions are _imprinted_ which means that one of the alleles is epigenetically silenced. It can be either paternal or maternal.