1204 



EMBRYOLOGY. 



The liver arises in the form of two diverticula or hollow outgrowths from the 

 ventral surface of that portion of the fore-gut which afterward becomes the 



Mesogastri ' tnt _^i(fl 

 anteriiis. 



7 



Liver.i 



Umbilical vei 



Border of the anterior 

 mesogastrium. 



W^t Bursa omentalis. 



- Pancreas. 



-Mesogastrium 



poster-ins. 

 Duodenum. 



-Great amentum. 



Transverse 

 mesocolon. 



Transverse colon. 



FIG. 768. Schematic figure of the bursa omentalis, etc. Human embryo of eight weeks. (Kollmann.) 



duodenum (Figs. 759, 760). The outgrowths, which represent the right and the 

 left lobes, respectively, of the adult liver, give off solid buds of cells, which grow 

 into columns or cylinders: these unite with one another in every direction to form 

 a close network, in the meshes of which are contained the capillary blood-vessels. 

 Some of these columns become hollowed out and form the bile-ducts, while the 



Diaphragm ' 



Stomach 



Greater curvature 



Anterior lamella of greater omentum 

 Posterior lamella of greater omentum 



Transverse colon 



Greater omentum 



Small intestine 



FIG. 769. Illustrating the development of the bursa onieutalis, cavity of the great omeatum or lesser sac. 

 F<ctal stage. * Lesser sac. (Hertwig.) 



remainder constitute the secreting structure. The minute ducts thus produced 

 unite to form the right and left hepatic ducts ; while the common bile-duct is 

 developed as a protrusion from the duodenal wall, and as it grows the liver becomes 

 shifted away from the duodenum. The gall-bladder and cystic duct are formed by 

 a hollow evagination from the wall of the common bile-duct. About the third 

 month the liver almost fills the abdominal cavity. From this period the relative 

 development of the liver is less active, more especially that of the left lobe, which 



