THE ORGANS OF DIGESTION. 26& 



duodenum (Fig. 218). Of the two buds, one is a minor process 

 which springs from the ventral aspect of the duodenum in 

 common with the hepatic diverticulum. This ventral bud only 



gl. bl. 

 common bile duct 



liuer ~--0^iy^h /MfJim— stomach 

 right hep. duct _& 



'orsal pancr. bud 



ventral pancr. bud 

 uodenum 



Fig. 21S. — The Pancreatic and Hepatic Processes of a 4th week human embryo. 

 (After Kollmann.) 



forms the lower part of the head of the pancreas. The greater 

 part is formed from a process which springs from the dorsal border 

 of the duodenum, nearer the stomach than the ventral process, 

 and grows into the dorsal mesogastrium above the stomach until 

 it reaches the spleen (Fig. 219). It unites in the mesogastrium 

 with the ventral bud. The ducts of both processes may persist, 

 the duct of the dorsal bud (duct of Santorini) opening half an 

 inch above the opening of the bile duct ; the duct of the ventral 

 bud (Wirsung's) opens with the common bile duct. The terminal 

 part of the duct of Santorini commonly becomes obliterated, and 

 even if it persists the secretion from the dorsal bud reaches the 

 duodenum mostly through the duct of the ventral bud — the duct 

 of Wirsung (Fig. 218). A third pancreatic bud has been observed 

 in the human embryo. It arises from the ventral aspect of the 

 gut, and corresponds to a third bud observed in the development 

 of the pancreas in lower vertebrates. 



The developing pancreatic processes are at first hollow, like the 

 primary liver process, but the secondary processes are solid and 

 cylindrical. They divide and re-divide, acquire lumina, and form 

 an acino-tubular gland. The capsular and connective tissue of 

 the pancreas are derived from the mesoblast of the dorsal 

 mesentery. 



