The authors chronicle the development of the gastrointestinal system, beginning with the embryology of the gastrointestinal tract through development of cells to hormones and enzymes. Each section provides a detailed explanation of the relevant stage of development so that residents and clinicians can better understand the interrelationships of each structure. Special attention is given to the latest cellular information and gene promoters in the regulation of intestinal development. Coverage of defects due to trauma and infections is also included.