And then that zygo travels into the uterus and inside the uterus we have that endometrium that the zygote implants into. And so the uterus functions to actually provide the nutrition that is needed for that zygote to actually grow. So the question is how exactly do these collection of cells know to carry out a specific type of function? Well, this is because of a process known as cell differentiation. And what cell differentiation is? It's when a single precursor stem cell basically divides and produces differentiates into many different types of cells.