insulin-secreting ( b ) cells , glucagon-secreting ( a ) cells , somatostatin-secreting ( d ) cells , and pancreatic polypeptide-secreting ( pp or f ) cells are distributed unequally among the four pancreatic lobes , with most of the a cells located in the third and splenic lobes and pp cells residing in both islet tissue and in acinar tissue .
C1327616
secreting
C0007634
cells