ABSTRACT
The embryologic development of the gallbladder must be discussed in the context of the embryology of the surrounding structures including the biliary tree and liver. The liver primordium is formed by proliferation of the cephalic portion of the hepatic diverticulum as it invades the septum transversum. Cellular proliferation and differentiation occurs to form liver cells and the epithelial lining of the intrahepatic biliary tree. Further development in rotation of structures in this area is thought to be due to a differential growth of the wall of the duodenum. It is interesting that gallbladder agenesis may occur in association with extrahepatic biliary atresia. This probably represents a similar mechanism of failure of recanalization. However, gallbladder agenesis, although rare, may occur in association with a normal biliary tree. An embryonic bend in the terminal part of the gallbladder-cystic duct outgrowth may account for deformities such as Phrygian cap, hourglass gallbladder, Hartmann's pouch, and diverticula.
