1738 HUMAN ANATOMY. 



organ represents the primitive ventral pancreas, the body and tail the dorsal seg- 

 ment. The duct of the ventral portion, which remains as the duct of Wirsung, forms 

 a communication with that of Santorini, and for a time the pancreas possesses two 

 outlets into the duodenum.. Usually the duct of Santorini loses its intestinal con- 

 nection and becomes tributary to the duct of Wirsung. Variations from this ar- 

 rangement are often encountered, the different combinations being due to deviations 



Diagrammatic reconstructions, showing development of pancreas and relations to liver-ducts, a, common bile- 

 duct ; b, hepatic and c cystic ducts; d, ri,g:ht and e left ventral pancreatic anlages ; /', dorsal pancreas and its 

 duct {g) ; h, junction of common bile (a) and ventral pancreatic (d ) ducts. After fusion of ventral and dorsal pan- 

 creas, rf becomes duct of Wirsung, "• duct of Santorini, and z' head of pancreas. 



from the ordinary progress of development as to the fusion of the two parts and per- 

 sistence of their canals. The areas of Langerhans are developed from the same 

 entoblastic outgrowths as give rise to the ordinary glandular tissue (Laguesse, 

 Pearce^). The connective-tissue septa are derived from the ingrowing mesoblast. 



Variations.- — The pancreas has been seen to surround the descending part of the duodenum. 

 Small accessory pancreases have been found in the walls of the intestine. Although usually in 

 the duodenum, they may be in the stomach or at the beginning of the jejunum, and occasionally 

 some distance from it. Presumably they are parts of the gland which became separated at an 

 early stage and were drawn by the growth of the intestine away from their original position.^ 



PRACTICAL CONSIDERATIONS : THE PANCREAS. 



Certain abnor?nalifies that may affect surgical procedures or may of themselves 

 produce symptoms of disease should be mentioned. Accessory pancreases are 

 found in various localities and may be mistaken for new growths. The anterior wall 

 and the two curvatures of the stomach and the walls of the small intestine, especially 

 the duodenum, are the situations in which such glands are most frequently found. 

 They have ducts opening into the intestine. 



An accessory gland has been found to the right of the duodenum entirely dis- 

 tinct from the main gland. Perhaps the most important anomaly is one in which 

 the gland completely surrounds the second part of the duodenum, constricting it and 

 causing dilatation of the first portion and of the stomach. Several cases have been 

 reported. The common bile-duct may also be contained within the head of the pan- 

 creas, as may the superior mesenteric vessels within its body. The accessory pan- 

 creatic duct may be absent, or there may be three ducts, all opening into the 

 duodenum. 



Movable Pancreas. — The gland may fall forward or downward (when it may 

 sometimes be felt below the stomach), or it may be a part of the contents of a dia- 

 phragmatic hernia, or may even — but wath great rarity — be contained within the sac 

 of an umbilical hernia. 



Injuries. — The situation of the pancreas behind the lesser peritoneal cavity and 

 the stomach and between the spleen and the duodenum, the partial protection it 

 receives from the costal arch, and the depth at which it lies render its uncompli- 



^ American Journal of Anatomy, vol. ii., 1903. 

 '^ Zenker : Virchow's Archiv, Bd. xxi., 1861. 



