396 



THE DIGESTIVE SYSTEM 



On approaching its termination the lining cells of an intercalary 

 duct are still more flattened and often acquire a considerable breadth. 

 They are elongated in the direction of the long axis of the tubule, and in 

 surface view have an irregularly polygonal outline (Bensley). They 

 pass into the acini in a peculiar manner. Instead of offering a direct 



FIG. 367. DRAWING OF AN INTERCAL- 

 ARY DUCT OP CAT, WITH THREE 

 BRANCHES ENDING IN ACINI TO 

 FORM CENTRO-ACINAL CELL GROUPS. 



The acinar cells contain numerous 

 basal filaments. X 750. 



FIG. 368. RECONSTRUCTION 

 MODEL OF THE HUMAN 

 PANCREAS. 



The intralobular duct gives 

 off long intercalary ducts, 

 which, after branching, end 

 in the acini. X 344. (After 

 Maziarski.) 



transition from the duct epithelium to that of the acinus the cells of 

 the former frequently appear as if telescoped into the lumen of the 

 acinus. Thus the centro-acinal cells (of Langerhans) are produced, 

 and consequently the centro-acinal cells correspond closely in appearance 

 with those of the intercalated ducts. They seem to occupy the lumen 

 of the acinus, and are only separated from the distal ends of the acinal 

 cells by the secretory capillaries which place the secreting cells in com- 

 munication with the lumen of the duct. The centro-acinal cells are 

 characteristic of the pancreatic acini. 



The Acini. The acini of the pancreas possess an irregular tubular 

 form with frequent alveolar dilatations. Their lining epithelium rests 



