Developmental biology is the study of how organisms grow and develop. It is a very broad field that incorporates a number of interrelated research interests. Embryology studies the developmental events that occur during the generation of gametes, fertilization, organogenesis, and creation of the embryo and fetus. Stem cell biology examines how stem cells control self-renewal, lineage specification, fate commitment, and differentiation. Regenerative biology is focused primarily on tissue repair and regeneration and thus embraces many of the goals of stem cell biologists to understand how to drive terminally differentiated cells back into a progenitor state.