During embryonic development, cell death and the control of cell survival play major roles for the formation of various organs. In the solid embryonic structures, such as morula and primordiums, starvation and hypoxia cause central cell death. Dying cells express the “eat-me” signal and are cleaned up by the neighbor cells through autophagy. As a result, a lumen or cavity was created that also named cavitation or lumenation. The lumens or caves not only bring nutrition and oxygen for the surviving cells, but also deliver signals for differentiation. Under appropriate conditions created by the cavitation, the surviving cells differentiated into functional mature cells and then form tissues and organs.