404 



THE DIGESTIVE SYSTEM 



gland and supply capillaries to the intralobular connective tissue about 

 the acini. Certain arterial branches also enter the islets and form a 

 specially rich plexus of broad capillaries (sinusoids) within these cell 

 groups. The veins return the islet blood by a similar course. 



The Lymphatics. 

 The lymphatics are 

 mostly confined to the 

 interlobular tissue, 

 where they are in re- 

 lation with the blood- 

 vessels. 



The Nerves. The 

 nerves are derived 

 from the sympathetic 

 system, and occur as 

 small trunks within 

 the interlobular con- 

 nective tissue. Nu- 

 merous small ganglia 

 occur in their course. 

 As in the salivary 

 glands the nerves sup- 

 ply the vascular walls. 

 About the secreting 

 acini they form a del- 

 icate network of 

 naked fibrils, from 

 which end branches 

 penetrate the base- 

 ment membrane and 

 terminate upon the 

 secreting cells. Lam- 

 ellar corpuscles are oc- 

 casionally found in the interlobular connective tissue of the pancreas. 

 Resume. Finally the attention of the student should be specially 

 directed to the presence of the pancreatic islets, the centro-acinar cells, 

 the very distinct inner granular and outer fibrillar zones of the secreting 

 cells, the thick walls of the interlobular ducts, the absence of intralobular 

 ducts except of the intercalary type, and the loose character of the inter- 

 lobular tissue as the distinguishing characteristics of the pancreas. 



FIG. 377. SECTION OF A PANCREATIC ISLET FROM 

 INJECTED SPECIMEN OF CAT'S PANCREAS TO SHOW 

 THE PROFUSE BLOOD SUPPLY. 



The capillaries were accurately drawn by aid of a 

 camera lucida. Only the nuclei of the islet cells are 

 indicated; one acinus is shown at the left. X 500. 



