| 1 | One part will become the placenta, the other the embryo. | |
| 2 | But they are difficult to make and require the use of an embryo or cloning technology. | |
| 3 | To find out, he and his colleagues grew embryonic heart cells on matrixes of differing stiffness. | |
| 4 | To win the bet, we will have to be able to predict the behaviour of almost all the cells in the embryo. | |
| 5 | Literally, you could not pick up a pencil off a bench if you were working with embryonic stem cells. |