Also when the embryo is developing sometimes we actually want to kill off certain cells in a certain area. For instance when we develop the fingers and the toes to actually develop these digits we have to destroy the cells in between these areas to basically go from this to this. And this process is a result of epitosis. So our cells synthesize these zymogens we call procast spaces and these procast spaces undergo proteolytic activation to form their active form cast spaces. And the cast spaces are these enzymes responsible for activating the process of apatosis. And again we want to undergo aptosis in one of two instances if we have infested cells or if we want to stimulate the proper embryological development in that developing embryo.