214 NORMAL HISTOLOGY AND ORGANOGRAPHY. 



The second duct, or duct of Santorini, loses its 

 connection with the alimentary canal and comes to 

 open into the duct of Wirsung. It is a very short 

 tube, inferior in position and secondary in impor- 

 tance. 



Histologically, the ducts are lined by a mucous 

 membrane of simple columnar epithelial cells that 

 are morphologically continuous and analogous with 

 the epithelial cells of the intestine. This mucous 



Fig. 160. Scheme showing relation of three adjoining alveoli to 

 excretory duct, illustrating origin of centro-acinal cells (Bohm and 

 Davidoff). 



membrane is ensheathed by a coat of connective- 

 tissue elements, fibers and cells, all of which are 

 associated with more or less fat. 



The acini resemble in form and size those of the 

 salivary glands. The parietal cells are absent. The 

 chief cells are columnar, the nucleus near the base of 

 the cell, and the cytoplasm loaded with zymogen 

 granules. During physiological activity these gran- 

 ules are greatly reduced. In addition, centro-acinal 



