THE PANCREAS 



1203 



of the duodenum a short distance above the hepatic diverticulum, and, growing 

 upward and backward into the dorsal mesogastrium, forms a part of the head and 

 uncinate process and the whole of the body and tail of the pancreas. The ventral 

 part appears in the form of a diverticulum from the primitive bile-duct and forms 

 the remainder of -the head and uncinate process of the pancreas. The duct of 

 the dorsal part (accessory pancreatic duct) therefore opens independently into the 

 duodenum, while that of the ventral part (pancreatic duct) opens with the common 

 bile-duct. About the sixth week the two parts of the pancreas meet and fuse 



Accessory pancreatic duct 

 Dorsal pancreas 



Ysntral pancreas 

 Pancreatic duct 

 Bile duct 



FIG. 1101. Pancreas of :i human embryo of five 

 weeks. (Kollmann.) 



Accessory pancreatic duct 

 Dorsal pancreas 



Bile duo, 



Ventral pancreas 

 Pancreatic duct 



FIG. 1102. Pancreas of a human embryo at end of 

 sixth week. (Kollmann.) 



and a communication is established between their ducts. After this has occurred 

 the terminal part of the accessory duct, i. e., the part between the duodenum and 

 the point of meeting of the two ducts, undergoes little or no enlargement, while 

 the pancreatic duct increases in size and forms the main duct of the gland. The 

 opening of the accessory duct into the duodenum is sometimes obliterated, and 

 even when it remains patent it is probable that the whole of the pancreatic secretion 

 is conveyed through the pancreatic duct. 



Lesser 

 Liver Stomach amentum Liver 



Left suprarenal 

 gland 



Right suprarenal 

 gland 



FIG. 1103. Schematic and enlarged cross-section through the body of a human embryo in the region of the 

 mesogastrium. Beginning of third month. (Toldt.) 



At first the pancreas is directed upward and backward between the two layers 

 of the dorsal mesogastrium, which give to it a complete peritoneal investment, 

 and its surfaces look to the right and left. With the change in the position of the 

 stomach the dorsal mesogastrium is drawn downward and to the left, and the right 

 side of the pancreas is directed backward and the left forward (Fig. 1103). The 

 right surface becomes applied to the posterior abdominal wall, and the peritoneum 

 which covered it undergoes absorption (Fig. 1104); and thus, in the adult, the gland 

 appears to lie behind the peritoneal cavity. 



Structure (Fig. 1105). In structure, the pancreas resembles the salivary glands. It differs 

 from them, however, in certain particulars, and is looser and softer in its texture. It is not 

 enclosed in a distinct capsule, but is surrounded by areolar tissue, which dips into its interior, 



