THE PANCREAS 



i8 7 



Of the two pancreatic anlages, the dorsal grows more rapidly and in 10 mm. 

 embryos forms an elongated structure with irregular nodules upon its surface. 

 Its distal portion is constricted to form a short duct. It lies in the greater omen- 

 turn between the duodenum and the stomach. The ventral pancreas is smaller 

 and develops a short slender duct which opens into the ductus choledochus. 

 As the latter elongates it bends dorsad and to the right of the intestine, while at 

 the same time the stomach and intestine rotate to the right. This shifts the duct 

 of the ventral pancreas so that it opens dorsally and somewhat to the left into the 

 bile duct. At the same time, the ventral pancreas is brought into close proximity 

 to the dorsal pancreas, and the duct of the latter is shifted to the left side of the 

 intestine (Figs. 178 and 180) . It is also carried further cephalad during the course 



Accessory pancreatic duct 

 Dorsal pancreas 



Ventral pancreas 

 Pancreatic duct 

 Bile duct 



Accessory pancreatic duct 

 Dorsal pancreas 



Bile duct 



FIG. 180. Two stages showing the development of the pancreas. A, at five wetks; B, at seven weeks 



(after Kollman). 



of development so that in the adult the interval between the ducts is from 10 to 



35 mm - 



In embryos of 20 mm. the tubules of the dorsal and ventral pancreatic an- 

 lages interlock (Fig. 180 B). Eventually, anastomosis takes place between the 

 two ducts and the duct of the ventral pancreas persists as the functional pan- 

 creatic duct of the adult. The proximal portion of the dorsal pancreatic duct 

 forms the accessory duct which remains pervious, but becomes a tributary of 

 the ventral pancreatic duct. The ventral pancreas forms part of the head 

 and uncinate process of the adult gland. The dorsal pancreas takes part in 

 forming the head and uncinate process and comprises the whole of the body and 

 tail. 



In 10 mm. embryos the portal vein separates the two pancreatic anlages and later they 

 partially surround the vein. The chief branch of the portal in the adult, the superior mesenteric 

 vein, thus passes through the pancreas, receiving the splenic vein which courses along and drains 



