232 



HISTOLOGY. 



In sections of the adult pancreas the islands are areas from .07 to 0.3 

 mm. in diameter, occupied by cords or groups of polygonal cells, the boun- 

 daries of which are often indistinct. 

 The nuclei, round or oval, contain chro- 

 matin in many small granules, together 

 with a few larger ones. The protoplasm 

 is finely granular and in certain of the 

 cells only, it is said to stain intensely with 

 saffranin. Sometimes the protoplasm 

 appears reticular. The islands may be 

 separated from the alveoli by a consider- 

 able layer of connective tissue in which 

 the elastic elements are infrequent, or by 

 a thin basement membrane. Sometimes 

 even the latter is absent. The endo- 

 thelium of the capillaries is surrounded 

 by a very small amount of reticular tissue. 

 The pancreatic and accessory pan- 

 creatic ducts are lined with simple col- 

 umnar epithelium which is surrounded 

 by an inner dense, and an outer loose 

 layer of connective tissue. The latter 

 contains some smooth muscle fibers 



which are gathered into sphincters at the outlets of the ducts. Oc- 

 casional goblet cells, and small glands resembling mucous glands, 



Intercalated 

 duct. 



Alveoli. 



Tubule. 

 FIG. 264. DIAGRAM OF THE PANCREAS. 



Inter- 

 calated 

 duct. 





Centroacinal cells. 



Zymogen granules. 

 A B 



FIG. 265. FROM SECTIONS OF A HUMAN PANCREAS. X 500. 



In sect ion A the granules are wanting, the elements of the intercalated duct are flat and dark; in section 

 B the granules are distinct, the cells of the intercalated duct are cubical and clear. 



