And so all these red cells eventually make their way around the green structure, around the blue structure and ultimately around the entire trophy blast, the purple section of this diagram. And so when we go from diagram four to diagram five, this is what we produce. So this imagination process along the primitive streak, the movement of the ectoderm cells into the red section, the formation of these red cells eventually pushes all these red cells and the mesodermal layer around the green structure, the blue structure and around this entire purple structure to form the following diagram. So this is basically our umbilical vesicle and this is basically the amniotic cavity where that fetus will be found. Now, what happens when we go from five to six is this section basically moves inwards. So it pushes this way and eventually we form an embryo that looks something like this.