Yixue Luo

1 Introduction The earliest stages of human embryo development initiate the dance of life but are hidden inside the mother. With dramatic morphogenesis happening from a ball of cells (known as the blastocyst) to a disc-shaped cellular structure (known as the epiblast), giving rise to all three germ layers and forming future organisms,[1] little is known about human developmental mechanisms. Human embryo culture complying with the globally agreed 14-day rule partially solves this problem.