1196 



DIGESTIVE SYSTEM 



from the latter's connection with the duodenum. A fusion of the two portions thus takes 

 place in this region, and at the same time there is established by anastomosis a connection be- 

 tween the terminal branches of the main duct of the dorsal portion — duct of Santorini — and the 

 branches of the main duct of the ventral portion — the duct of Wirsung. With further devel- 

 opment the duct of Wirsung develops into the main pancreatic duct, the duct of the dorsal 



Fig. 958. — Diagram SHO■w^NG the Relations of the Pancreas to the Primitive Mesen- 

 tery. (Poirier-Charpy.) 

 Aorta 



Left gastric art. 



Dorsal mesogastrium (pf.rtion 

 becoming adherent) 



Coeliac art. 



Hepatic art. 



Right gastro-epiploic 



art. 



Superior pancre- 



atico-duodenal 



art. 



Head of pancreas 



Superior mesen- 

 teric art. 



Mesentery 



Tail of pancreas 

 Splenic art. 



Body of pancreas 



Dorsal mesogastrium 

 (portion fusing with 

 transverse meso- 

 colon) 



portion (duct of Santorini) either losing its connection with the duodenum or remaining as the 

 accessory pancreatic duct. 



Thus of the adult gland, only the lower portion of the head is derived from the primitive 

 ventral anlage, although the duct of the latter drains nearly the entire adult gland. The upper 

 part of the head of the pancreas, and all of the body and tail are derived from the dorsal anlage; 

 although most of its duct joins with the duct of Wirsung to form the main pancreatic duct, 

 only a small part persisting as the accessory duct of Santorini. 



Fig. 959. — Section op Human Pancreas, Magnified, Showing Several Islets of 

 Langerhans. (Radasch.) a, Interlobular connective tissue, containing an interlobular duct, 

 c, b, Capillary, d, Interlobular duct, e, Alveoli. /, Islet of Langerhans. 



During the early .stages in the development of the pancreas the cntodermal buds from 

 which it forms grow into tlie mesoduodenum, and later the dorsal mesogastrium. With the 

 rotation of the stomach and the consequent change in the position of the mesogastrium and its 

 partial fusion with the abdominal wall, the pancreas assumes a retroperitoneal position. This 

 18 illustrated by fig. 958. The head of the pancreas is involved in the rotation of tlie primitive 



