CHAPTER XIII 



THE DISEASES OF THE INSULAR APPARATUS OF THE PANCREAS 

 AND THEIR RELATION TO DIABETES MELLITUS 



A description of the pathology of the inner secretion of the pancreas 

 offers beforehand many greater difficulties than that of other ductless glands, 

 especially if the clinical manifestations are chiefly considered. The pancreas 

 is not, like the other ductless glands, exclusively a gland with internal se- 

 cretion. It belongs to the most important glands of external secretion; and 

 anatomically shows chiefly the structure of one of these. Actually the 

 physiology and pathology of the external secretion of the pancreas was for a 

 long time the subject of investigation, before clinical observations, and then 

 the experiments on the total extirpation of the pancreas, led us to think of 

 the possibility that the pancreas might have an internal as well as an external 

 secretion. 



Historical Development. Already Bouchardat had observed sclerotic 

 alterations of the pancreas in some cases of diabetes mellitus, and on the 

 ground of these observations had expressed the opinion that the cause of 

 human diabetes depended on a disease of the pancreas. A secure experi- 

 mental foundation 1 for this view was first created by the celebrated ex- 

 periments 'of v. Mering and Minkowski. These investigations showed that 

 total extirpation of the pancreas in dogs, in addition to the disturbances 

 of absorption due to the absence of the pancreatic juice, leads regularly to 

 an excretion of sugar, indeed even to a severe, fatally ending, diabetes. 



First through this discovery was the interest of pathological anatomists 

 turned in general toward the pancreas. In the course of the next decade there 

 followed numerous statments as to various alterations of the pancreas in 

 diabetes mellitus, sclerotic changes, inflammatory processes, etc. ; yet in spite 

 .of the weight of the experimental finding, we could not overlook the fact that 

 in many cases of severe diabetes mellitus the pancreas showed no demon- 

 strable pathologico-anatomical alteration and that, on the other hand, in 

 many cases of high-grade destruction of the pancreatic tissue, diabetes was 

 entirely absent. The question assumed another aspect when attempts were 

 made to bring the islands formerly described by Langerhans into relation 

 with the inner secretion of the pancreas. While the glandular acini furnish 

 the external secretion, the islands of Langerhans might constitute an em- 

 bryologically independent tissue element distributed throughout the entire 

 pancreas, which might give off directly into the blood path a hormone im- 

 portant for carbohydrate metabolism. Especially important for this view 



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