Here's some more info about the progress of Baby Walery thanks to fitpregnancy.com

the embryo is about two millimeters long, about the size of a grain of sand. The baby transforms into a bundle of cells organized in a C-shape with a top, bottom, front, and back. A groove has developed on the embryo's back, which will seal and develop into the neural tube (which later will become the spinal cord). At this point, the tube already has a wider, flatter top that will grow into the baby's brain. A bulge has developed in the center of the embryo, which will soon become a tiny U-Shaped tube which will form the heart. The embryo is encased in protective membranes and attached to a yolk sac, which manufactures the embryo's unique blood cells.