Researchers at the University of Cambridge have used mouse stem cells to make model embryos with a brain, a beating heart, and the beginnings of all the other organs in the body.
The team, led by Professor Magdalena Zernicka-Goetz, made the model embryo without using eggs or sperm.
Instead, they used stem cells, which are the master cells of the body and can turn into almost any type of cell.
In the lab, the researchers imitated natural processes by getting the three types of stem cells that are found in young mammals to the point where they start to talk to each other.
Stem cells organised themselves into beating hearts, brain foundations, and the yolk sac, where the embryo grows and gets food in its first weeks.
Professor Zernicka-Goetz said, "Our mouse embryo model not only grows a brain, but also a beating heart and all the other parts that will go on to make up the body."
A big step forward in the study is being able to make the whole brain, especially the front part, which has been a big goal in making synthetic embryos.
Scientists found that the extraembryonic cells talk to the embryonic cells both chemically and mechanically, or by touch, to guide the development of the embryo.
Our results show that embryonic stem cells and two types of stem cells from outside the embryo can re-create mammalian development from gastrulation to neurulation and early organogenesis.