This gland is located in the loop of-duodenum. It is emptied by its two ducts, (in man and dogs), and sometimes several additional ducts, into the duodenum.
It is remarkable in producing both an external and internal secretion. The bulk of the gland has a racemose structure resembling that of the salivary glands.
The acinar cells show a peripheral clear zone and a central zone containing zymogen granules which discharge into the lumen during the period of secretory activity.
The main duct of the gland communicates with the bile duct at the ampulla of the bile duct (ampulla of Vater) and discharges the secretion into the duodenum through the sphincter of Oddi.
Embedded within the pancreatic acinar tissue there is a relatively small amount of cellular tissue, quite different in appearance, which occurs in little groups the interalveolar cell-islets or the islands of Langerhans. This tissue produces the internal secretion called insulin.
The pancreatic juice secreted by pancreatic gland reaches the intestine through the duct of Wirsung which usually joins with the common bile duct before opening into the first part of the duodenum.
As soon as the food enters the duodenum, a series of neurogenic and hormonal mechanisms come into play and maintain a secretion of fluids into the duodenum, where they mix with the acid chyme from the stomach.
The most important feature of the pancreatic juice is its high concentration of bicarbonate ions and enzymes capable of hydrolyzing virtually any type of food constituents.