CHAP. III.] MINUTE STRUCTURE OF THE PANCREAS. 191 



Micro-cnemi- "Water causes the outer zone rapidly to swell up 

 cai reactions .whilst the granules of the inner zone in great part 

 ^ ic th c e el P g ancre - become indistinct. 



"Dilute solution of caustic potash or soda (containing 

 only 0*1 per cent.) dissolves the granules almost instantaneously and 

 ultimately the whole cell. 



"Dilute acetic and mineral acids of all degrees of concentration 

 render the outer zone so turbid, by causing a granular precipitate, 

 that the distinction between the two zones of the cell vanishes. 

 Glacial acetic acid on the other hand renders the cells clear, merely 

 allowing some fine granules to be perceived, whilst the nuclei come 

 out sharply 1 ." 



It was remarked by Claude Bernard 2 that the pancreatic secreting 

 cells are dissolved with great ease by bile. This is to be explained 

 by the bile being a liquid which permits tryptic proteolysis to 

 proceed with ease. 



Vascular and Nervous Supply of the Pancreas. 



Vascular The pancreas in man receives branches from 1st 



supply. t k e ne p a ti c artery, 2nd the splenic artery, and 3rd the 



superior mesenteric artery; the branches from these arteries form 

 numerous anastomoses. A capillary network surrounds the ultimate 

 acini, but by no means closely, so that often the secreting cells are 

 at a considerable distance from the nearest capillaries. 



The veins of the pancreas which run by the side of the arteries 

 empty into the superior mesenteric and into the splenic veins, so 

 that all the blood which leaves the organ has to pass through the 

 liver. 



Nervous In man the nerves of the pancreas are derived 



supply. primarily from the solar plexus, but for the most part 



they are immediately derived from the hepatic, mesenteric, or 

 splenic plexuses. They first accompany the arteries, but after 

 reaching the substance of the gland, they follow a separate course. 

 According to Pfliiger the fibres of the pancreatic nerves are medul- 

 lated. Kiihne and Lea, and Heidenhain, however, assert that they 

 are non-medullated. Besides nerve fibres, ganglion cells are abun- 

 dantly scattered through the gland. 



SECT. 2. THE SECRETION OF PANCREATIC JUICE. 



The secretion of the pancreatic juice is one of those phenomena 

 which it is impossible to study except with the aid of experiments 

 on the lower animals. 



1 Heidenhain, Hermann's Handbuch, Bd. v. Th. 1, s. 175. 



2 Claude Bernard, Lecons de Phys. Experim. Vol. ii. 



OPTHF 



"UNIVERSITY 



