1912.] 



Islets of Langerhans to the Pancreatic Acini. 



87 



DESCRIPTION OF PLATES 2 and 3. 



Fig. 1. — Normal islet in the charged pancreas of the dog. a, A cells of Lane, b, B cells 



of Lane, c, centroacinous cells, r.b.c, red blood corpuscles. Notice the 

 arrangement of the large round zymogen granules in the surrounding acini, 

 also the distribution of the mitochondrial filaments. The borders of the 

 islet are extremely irregular and no limiting membrane is present. 



Fig. 2. — Normal islet in the exhausted pancreas of the dog. a, A cells of Lane, b, B cells 



of Lane. Notice the distribution of their granules along the capillaries, which 

 are indicated by the red blood corpuscles (r.b.c). c, centroacinous cells. 

 d, duct cells, which are continuous with those of the islet below and low down 

 on the right, z, exhausted acini. Notice the prevailing absence of zymogen 

 granules, the presence of some mitochondrial filaments, and the vacuolisation 

 of the cells. In the low right-hand corner a small group of acinous cells is cut 

 off from the rest by a small duct. 



Fig. 3. — Normal islet in the charged pancreas of the guinea-pig. a, A cells of Lane, 



undifferentially stained, b, B cells of Lane, containing fine blue granules. 



s, acini, containing zymogen granules. 

 Fig. 4. — Normal islet in the exhausted pancreas of the guinea-pig. a, A cells of Lane. 



b, B cells of Lane, m, acinous cells, containing "Mankowski" granules. 



2, acini without zymogen granules. 

 Fig. 5. — Group of duct cells and atrophied acini (from 26-day fragment), c, centroacinous 



cells, d, masses of duct cells, which partly retain their tubular arrangement 

 and occupy the central part of the figure. Notice the resemblance of these 

 cells in the arrangement of their mitochondrial filaments and granules to the 

 islet of fig. 6. 



Fig. 6. — Islet containing only a few typical B cells (from 26-day fragment). 6, B cells of 



Lane, d, duct cells (poorly preserved), z, acini containing zymogen granules. 

 Notice the small number of typical B cells. The rest of the islet cells might, 

 from their appearance, be duct cells or A cells. Compare with figs. 5 and 1. 



VOL. LXXXVI. — B. 



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