All cells in the embryo contain the same genetic information from the zygote. All cells in the embryo are genomically equivalent.

Differences that arise between cells are due to differential gene activity, whereby transcription factors bind to enhancers, activating different genes in different cells. This was demonstrated by the blastomere isolation experiment, nuclear transplantation experiment and in situ hybridization.

Embryogenesis is a process of generating increasing complexity by the action of different genes in different cells. All cells in an embryo are genomically equivalent. Increasing complexity arises progressively via cell-cell interactions, causing differential gene expression that controls proliferation, differentation, interaction, shape and movement.