THE PANCREAS 



1341 



of the duodenum, and usually terminates by an orifice common to it and the 

 common bile duct upon the summit of an elevated papilla, situated at the inner 

 side of the descending portion of the duodenum, three or four inches (7.5 to 10 

 cm.) below the pylorus (Figs. 1079 and 1080). 



Sometimes the pancreatic duct and common bile duct open separately into the 

 duodenum (Fig. 1013). Frequently there is an accessory duct, which is given off 

 from the canal of Wirsung in the neck of the pancreas and passes horizontally 

 to the right to open into the duodenum about an inch above the orifice of the main 

 duct. This is known as the duct of Santorini (ductus pancreaticus accessorius 

 [Santarini]) (Fig. 1083). 



RECTUS MUSCLE. 



8th Costal CartUane. 



7th Costal Cartilage. 



7th Rib. 



^~8th Rib. 



9th Rib. 



DIAPHRAGM. 



Abdominal Aorta. 



ItthRib. llthBSbt 



FIG. 1084.- Transverse section through the middle of the first lumbar vertebra, showing the relations of the 



pancreas. (Braune.) 



The pancreatic duct, near the duodenum, is about the size of an ordinary quill; 

 its walls are thin, consisting of three coats, an external fibrous, a middle muscular, 

 and an internal mucous; the latter is smooth, and furnished near its termination 

 with a few scattered follicles. 



Structure. 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, and connects 

 the various lobules of which it is composed. Each lobule, like the lobules of the salivary 

 glands, consists of one of the ultimate ramifications of the main duct, terminating in a number 

 of cecal pouches or alveoli, which are mainly grape-like. The minute ducts connected with the 

 alveoli are narrow and lined with flattened cells. The alveoli are almost completely filled with 

 secreting cells, so that scarcely any lumen is visible. In the centre of the end-tubules flat cells 

 are frequently found. They are continuations into the tubules of the duct epithelium. These 

 cells are known as the centro-acinar cells of Langerhans. The true secreting cells which line 

 the wall of the alveolus are very characteristic. They are pyramidal or rounded in shape and 

 present two zones an outer one clear and finely striated next the basement membrane, and an 

 inner granular one next the lumen. The highly refracting granules are known as zymogen 

 granules. During digestion the granules gradually disappear and the cells become clear. Dur- 

 ing fasting the granular zone occupies more than one-half of the cell (Szymonowicz). In some 

 secreting cells of the pancreas is a spherical mass, staining more easily than the rest of the cells; 



