Scientists have grown an entity very close to a human embryo – without using sperm, eggs or a uterus.
The embryo even released hormones that turned a lab pregnancy test positive.
Researchers at the Weizmann Institute of Science in Israel have created the complete models of human embryos from stem cells generated in the lab.
Professor Jacob Hanna, who led the research team, said: ‘The drama plays out in the first month; the remaining eight months of pregnancy consist mainly of growth.”
Pictured: The 14-day embryo, including the yolk sac (yellow) and the part that will become the embryo itself, topped by the membrane (blue) – all encased in cells that will become the placenta (pink)
The artificial embryo model had all the elements a 14-day human embryo should have, including the placenta, yolk sac, membranes, and other external tissues.
The hope is that the model will enable researchers to ethically work out what happens during a human embryo’s first few weeks after a sperm fertilizes an egg.
Many miscarriages and birth defects occur during this period, but little is known about it at the moment.
Professor Hanna said: ‘That first month is still largely a black box. Our stem cell-derived human embryonic model provides an ethical and accessible way to look into this framework.
“It closely mimics the development of a real human embryo, particularly the emergence of its exquisitely fine architecture.”
Until now, models of human embryos have been inaccurate because they lack cell types critical to embryo development, including cells that make up the placenta and membrane.
They also did not grow beyond the 14-day limit.
The research was published today in the journal Nature.