Embryology: Scientists crack open 'black box' of development and see a 'rosette'

We know much about how embryos develop, but one key stage -- implantation -- has remained a mystery. Now, scientists have discovered a way to study and film this 'black box' of development. This new method revealed that on its way from ball to cup, the blastocyst becomes a 'rosette' of wedge-shaped cells, a structure never before seen by scientists.