182 



THE DIGESTIVE SYSTEM 



loose fibroelastic tissue. The secreting end-pieces, which may be 

 tubular or short and roughly spherical, are formed of pyramidal cells. 

 The cytoplasm of these cells is lighter staining toward the lumen 

 and more deeply staining with striated appearance in the basal 



Fig. 117. — Diagrams showing structure of pancreas. ^4, a small excretory duct 

 with its branches terminating in secretory end pieces. The intercalated ducts 

 extend part way into the end-pieces. B, longitudinal section of an end-piece, showing 

 centro-acinar cells (involuted intercalated duct) and the secretory cells which have 

 basal striations and secretory granules toward the lumen. The secretory cells are 

 serous in type. (', cross-section of a secretory end-piece distal to centro-acinar cells. 



region. (Fig. 117.) The lighter portion contains coarse zymogen 

 granules, which are ])r('sumably forerunners of the enzymatic secre- 

 tions. In the basal half of the cell there is a nucleus with a chro- 

 matin network and one or more nucleoli. In sections, centro- 

 acinar cells may occupy the lumen of many acini along the inner ends 



