One part will become the placenta, the other the embryo.

But they are difficult to make and require the use of an embryo or cloning technology.

To find out, he and his colleagues grew embryonic heart cells on matrixes of differing stiffness.

To win the bet, we will have to be able to predict the behaviour of almost all the cells in the embryo.

Literally, you could not pick up a pencil off a bench if you were working with embryonic stem cells.