During the first hours of an embryo’s development, specialized molecules called pioneer transcription factors unravel parts of its DNA to activate the encoded genes. Which gene is activated and when has to follow a set schedule so that genes that are only needed at later stages of development are not activated too early—such as those that trigger the differentiation of specialized cell types.
Click here for original story, A better understanding of gene regulation in embryonic stem cells
Source: Phys.org