By this time your developing baby is a little ball of cells that's officially referred to by scientists as a blastocyst:-

http://www.babycenter.com/6_your-pregnancy-2-weeks_6000.bc

 It has an inner cell mass that will become the embryo itself, a fluid-filled cavity that will become the amniotic sac, and an outer cell mass that will become the placenta, the pancake-shaped organ that delivers life-sustaining oxygen and nutrients to your baby and carries away waste products.