The liver, gallbladder and the biliary duct system arise as a bud of the endodermal epithelium at the distal end of the foregut. The hepatic diverticulum (liver bud) grows into the septum transversum. Septum transversum is the mesodermal plate between the pericardial cavity and the stalk of the yolk sac. Cranial part of the septum transversum forms the tendinous portion of diaphragm, while its caudal part contributes to the ventral mesogastrium. The large part of the liver bud forms the parenchyme of the liver and billiary apparatus. The fibrous, hemopoietic tissue and Kupffer cells derive from the mesenchyme of the septum transversum. A small caudal portion of the liver bud expands to form gallbladder and bile duct.

1. Esophagus
2. Hindgut
3. Stomach
4. Tracheobronchial diverticulum
5. Duodenum
6. Midgut loop
7. Septum transversum
8. Cloaca
9. Gallbladder
10. Liver
11. Cloacal membrane
12. Pancreas
13. Heart
14. Ventral mesogastrium
15. Dorsal mesogastrium

1. Liver bud
2. Stomach
3. Gallbladder
4. Ventral pancreatic bud
5. Dorsal pancreatic bud

1. Liver bud
2. Dorsal pancreas
3. Gallbladder
4. Ventral pancreas
5. Cystic duct
6. Hepatic duct
7. Bile duct

1. Stomach
2. Gallbladder
3. Cystic duct
4. Hepatic duct
5. Bile duct
6. Pancreas
7. Accessory pancreatic duct
8. Main pancreatic duct
9. Ventral pancreatic duct