Final answer:
Organogenesis is the theory that new organs and tissues form completely new each generation. It is the process in which the three germ layers formed during gastrulation give rise to different organs in the animal body.
Step-by-step explanation:
The theory that new organs and tissues form completely new (de novo) each generation is termed organogenesis. Organogenesis is the process in which the three germ layers formed during gastrulation give rise to different organs in the animal body. This process is characterized by rapid and precise movements of cells within the embryo.