4 “We know so little about the very early stages of human development ... sequence into one of the two cells of the zygote. Thus, they could determine the contribution of each cell to the development ...

While experts aren’t sure why a zygote may not progress to the next stage of development, they think it may be due to chromosomal abnormalities and other factors. Often a woman may not know she ...

The zygote inherits two fully active X chromosomes and begins re-inactivation of the paternal X chromosome (XP) at the 4- to 8-cell stage ... pre-implantation development. Silencing becomes ...