Scientists Grow Whole Model of Human Embryo, Without Sperm or Egg

I can see the trophoblast, which would normally become the placenta, enveloping the embryo. And it includes the cavities - called lacuna - that fill with the mother's blood to transfer nutrients to the baby.

There is a yolk sac, which has some of the roles of the liver and kidneys, and a bilaminar embryonic disc - one of the key hallmarks of this stage of embryo development.

closer these models come to an actual embryo, the more ethical questions they raise.

"The work has, for the first time, achieved a faithful construction of the complete structure [of a human embryo] from stem cells" in the lab, "thus opening the door for studies of the events that lead to the formation of the human body plan,"

The researchers stress it would be unethical, illegal and actually impossible to achieve a pregnancy using these embryo models - assembling the 120 cells together goes beyond the point an embryo could successfully implant into the lining of the womb.