i 7 8 



THE ENTODERMAL CANAL AND THE BODY CAVITIES 



gall bladder and ducts have become longer and more slender. The hepa- 

 tic duct receives a right and left branch from the corresponding lobes of 

 the liver. The gall bladder is without a lumen up to the 15 mm. stage. 

 Later its cavity appears, surrounded by a wall of high, columnar epithelium. 



flepatic duct 



Ductus choledochus 



Ventral pancreas 



Gall bladder 



Cystic dud 



Cystic duct 

 Ductus choledochus 



Ventral pancrea 



Duodenum 



Duct of dorsal' 



pancreas 

 Head of dorsal pancreas ' 



Duodenum 



Tail of 

 dorsal 

 pancreas 



FIG. 185. Reconstructions showing the development of the hepatic diverticulum and 

 pancreatic anlages. A, 7.5 mm. human embryo (after Thyng), X 50; B, 10 mm. human 

 embryo, X 33- 



The glandular portion of the liver develops fast and is largest relative 

 to the size of the body at 31 mm. (Jackson). In certain regions the liver 

 tissue undergoes degeneration, and especially is this true in the peripheral 



FIG. 186. Diagrams of three stages of the portal and hepatic veins in a growing liver: 

 a, Hepatic side; d, portal side; b and c, successive stages of the hepatic vein; e and/, successive 

 stages of the portal vein (Mall). 



portion of the left lobe. In general, the external lobes of the liver are 

 moulded under the influence of the fetal vitelline and umbilical trunks. 

 The development of the ligaments of the liver is described on p. 193. 



