Illustration of the main stages of pancreas development in the mouse embryo, which are largely equivalent to the process in human development. Initial budding of the dorsal bud is followed by ventral bud formation, both of which can be detected by E10.5. Both buds grow and at E11.5, due to twisting of the developing gut tube. The ventral bud moves dorsally until it sits alongside the larger dorsal bud. The two buds then fuse (E12) to form the mature pancreas.