But from another perspective, the zygote is a very, very special cell. And that's because following the formation of the zygote the zygote somehow knows to begin a set of very, very complicated and very intricate processes we call embryological development that allows the zygote to actually eventually develop into the highly specialized and highly complex tissues and organs and systems found within the human body. Such as, for example, the cardiovascular system that consists of the hearth and the blood vessels the nervous system that consists of the brain and the spinal cord as well as the other ganglia found in the body. It also creates the bone, the kidneys, the pancreas, the liver and many other organs of our body. So the question we want to address in this lecture is what exactly allows embryological development to actually take place in the first place? So as it turns out, there are four individual processes that have to work together for embaloglogical development to actually take place the way that it does in our body.