A new embryologic hypothesis of annular pancreas

Annular pancreas is a developmental anomaly of the pancreas. There are two major hypotheses concerning development of the annular pancreas from the ve ntral pancreatic anlage; adhesion of the right ventral anlage to the duoden al wall (Lecco's theory), and persistence of the left ventral anlage (Baldw in's theory) reported in 1910, but each theory has some problems and can ac count for only a few types of annular pancreas. We report a new embryologic hypothesis of annular pancreas which can account for the developmental mec hanism of three types of arrangement of annular ducts. The tip of the left ventral anlage adheres to the duodenum and stretches to form a ring. Whethe r the tip is proximal or distal to the bile duct creates several arrangemen ts of the annular duct.