For the first time ever, scientists have managed to grow what they are referring to as an “entity that closely resembles a human embryo” without using an egg, sperm or a womb.  The “embryo model” was created by the Weizmann Institute using stem cells in order to try and replicate the creation process of an embryo. Outside of its shocking likeness to a 14 day old embryo, it was also responsible for emitting hormones that triggered a positive result in a pregnancy test. The idea behind the embryo modelling is really to help us better understand the earliest stages of conception and embryo development and the biological and ethical implications this stage has a determiner on the potential life that is resultant of that embryo.

This ground-breaking study has been published in the Nature journal, is the first of its kind and looks to study embryos without all the ethical caveats that come along with one that is the product of sperm and egg as that calls into question political and religious views and definitions of what constitutes as a ‘human baby’ as well. This also removes the legal claim to an embryo as it’s entirely developed from stem cells and not attached to two distinct DNA contributors. The stem cells themselves were “reprogrammed” meaning that they have the potential to become any type of tissue within the body. According to the scientists, different chemicals were then added to the mix in order to “coax these stem cells into becoming four types of cell found in the earliest stages of the human embryo.” The first of which is known as epiblast cells which are responsible for the formation of the embryo, the trophoblast cells which become the placenta. Outside of these hypoblast cells and extraembryonic mesoderm cells also play a role in the final creation of a synthetic human embryo. The final composition of cells is a precise mix of 120 cells.

“I give great credit to the cells – you have to bring the right mix and have the right environment and it just takes off,” says the project’s Professor Hanna, “That’s an amazing phenomenon.” The 14 day window is a significant one, as in most countries this is the “legal cut-off for normal embryo research.” “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, says Prof Alfonso Martinez Arias, from the department of experimental and health sciences at Pompeu Fabra University.