THE PANCREAS. 



301 



bans. Peculiar cells, wedged in here and there between the secre- 

 tory cells, but resting on the membrana propria, have also been 

 observed. They undoubtedly are sustentacular cells of the gland 

 (cuneate cells, Podwyssotzki, 82). 



The incinbrana propria of the alveoli is probably homogenous. 

 Immediately adjoining it is another delicate but firm membrane, 

 consisting of fibrils whose structure in many respects resembles that 

 of the reticular fibers (Gitterfasern) in the liver and spleen, but which 

 are here in relation to the alveoli (Podwyssotzki, 82). 



In warm- and cold-blooded animals, groups of cells differing in 

 arrangement, size, and structure from the secretory cells, are found 

 among the gland tubules and alveoli of the pancreas ; these are 

 known as the intcrtubular cell-masses, or areas of Langerhans. They 

 are most numerous in the splenic end of the pancreas (Opie). They 



Outer zone of 

 a secretory- 

 cell. 



Connective . 

 tissue. 



Larger gland 

 duct. 





- Centro-acinal 

 cell. 



Centro-acinal 

 cell. 



- Ivi.ermediate 

 tubule. 



Inner granular 

 zone of secre- 

 tory cells. 



Fig. 242. From section through human pancreas ; X45 (sublimate). 



consist of slightly granular cells, smaller than the secretory cells 

 of the alveoli, arranged in the form of anastomosing trabeculae, with 

 irregular spaces, varying in size, separating the trabeculae. Dogiel 

 (93) has shown that in a well-preserved human pancreas treated 

 by the chrome-silver method, in which the gland ducts even to 

 their finest intra-alveolar branches were well stained, no ducts were 

 found in the areas of Langerhans. Such areas are, in the human 

 pancreas, usually separated from the surrounding gland tissue by a 

 small amount of connective tissue. They possess a blood supply, 

 consisting of relatively large capillaries found in the spaces formed 

 by the trabeculae of cells above mentioned. The areas of Langer- 

 hans have been variously interpreted. They have been looked 

 upon as small areas of gland tissue in process of degeneration, or 



