Every human being grows out of three tubes At least, that's what we can call it in terms of embryogenesis☝🏻 In the future, one of the tubes will become the cardiovascular system. The second one will develop in all directions from the axis of the spinal column and become the nervous system. This is the heart and nerve tube. And the third one begins with the mouth and ends in the lower back. This is the intestinal tube, our future digestive system.