SECRETING ALVEOLI. 139 



septa (interlobular) of similar tissue which traverse the pan- 

 creas and divide it into lobes and lobules ; and of delicate 

 connective tissue penetrating between the individual alveoli 

 which make up the lobules, and providing them with base- 

 ment-membranes. 



The larger vessels, ducts, and nerves are conveyed through 

 the organ in the interlobular connective tissue. 



The larger (or interlobular) divisions of the ducts are lined 



FIG. 59. 



Portion of pancreas (Bohm and Davidoff). a, large duct: 6, beginning ducts; 

 c, d, e, secreting alveoli ; g, sustentacular connective tissue. 



with simple columnar epithelium ; the small ductules with flat- 

 tened epithelium-cells. 



The secreting alveoli are rather tubular in form, of the 

 serous type, and are lined with a single layer of spheroidal 

 or columnar glandular epitheli urn-cells. The lumen of the 

 alveoli also sometimes contains small cells, called centro-acinal 

 cells. 



The cells lining the alveoli vary according to the stage of 

 secretion. Before secretion these cells are distended, and the 

 zone toward the lumen is clear and contains coarse zymogen- 



