Liver (Hepar)

Abstract

The hepatic diverticulum is the primordial outgrowth of cells destined to form the secretory tubules of the liver, its duct system and the gallbladder. It arises ventrally during the 4th week from the entodermal lining of the gut, and when it is first recognizable, it lies just caudad to the heart. A maze of anastomosing and branching cell cords grows ventrad and cephalad. The distal portions of these cords give rise to the secretory tubules of the liver, and their proximal portions form the hepatic ducts. The growing hepatic tubules push between the 2 layers of splanchnic mesoderm which form the ventral mesentery and spread these 2 layers apart. The investing mesodermal layers form the fibrous connective tissue capsule of the liver and the interstitial connective tissue of the liver lobules.