CHANGES IN PANCREATIC CELLS. 167 



gland. When digestion commences, the cells undergo a slight 

 change in form, so that each individual cell is more distinctly 

 seen, and its angles are retracted, giving a notched appearance to 

 the margin of the acinus. The blood supply during this period 

 is much increased, red arterial blood flowing from the veinlets of 

 the gland. At the same time the granules are diminished in num- 

 ber, escaping at the free central margin of the cells into the lumen 

 toward which they appear to crowd, leaving the outer zone once 

 more clear and free from granules, while the lumen of the sac- 

 cule and of the ducts are filled with secretion. 



Let us then examine a single cell ; during the period of rest 



FIG. 70. 



One Saccule of the Pancreas of the Rabbit in different states of activity. A. After a 

 period of rest, in which case the outlines of the cells are indistinct, and the inner zone, 

 i.e., the part of the cells (a) next the lumen (c), is broad and filled with fine granules. 

 B. After the gland has poured out its secretion, when the cell outlines (d) are clearer, 

 the granular zone (a) is smaller, and the clear outer zone is wider. (Ktthne and Lea ) 



with a comparatively poor supply of blood, the cell receives its 

 normal nutrition, which is accompanied by an accumulation of 

 granules in the protoplasm next the free side of the cell. During 

 secretion these granules are pushed out of the cell, and seem in 

 some way to form the secretion. 



It will be seen immediately that one of the most important 

 functions of the pancreatic juice is the formation of peptone from 

 proteid, which operation is carried out by a special ferment 

 called trypsin. It has been found that this ferment can only be 

 obtained from the active pancreas, and that the wider the inner 



