So these are the questions we're going to address in this lecture. So let's begin with the zygote stage. So when we form the zygote, the next step that happens is mitosis and the zygote begins to divide. So it forms this two cell embryo stage where we have two identical cells. This process continues. We form four cells, eight cells, 16 cells, 32 cells and so on and so on until we form the billions of cells that are found inside the individual organism.