DIGESTION 



187 



from fifteen to twenty centimeters in length, six in breadth, and two and a 

 half in thickness. It is usually divided into a head, body, and tail The 

 head is directed to the right side and is embraced by the curved portion of the 

 duodenum; the tail is directed to the left side and extends as far as the spleen 



Pancreatic ducts. Common bile-duct- 



Tail. 



FIG. 79. PANCREAS AND DUODENUM REMOVED FROM THE BODY AND SEEN FROM 

 BEHIND. THE GLAND is CUT TO SHOW THE DUCTS. (Landois and Stirling.) 



(Fig. 79). The pancreas communicates with the intestine by means of a 



duct. This duct commences at the tail and runs transversely through the 



body of the gland. As it approaches the head of the gland it gradually in- 



crea ses in size until it measures 

 about two or three millimeters 

 in diameter. It then curves 

 downward and forward and 

 opens into the duodenum. In 

 its course through the gland it 

 receives branches which enter 

 it nearly at right angles. The 

 pancreas is richly supplied with 

 blood-vessels and nerves, the 

 latter coming from the solar 

 FIG. 80. FIG. 81. plexus. 



ONE SACCULE OF THE PANCREAS OF THE RABBIT Histologic Structure. In 



IN DIFFERENT STATES OF ACTIVITY. Fig. 80. 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 rilled with 



fine granules. Fig. 81 . 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. (Kuhne and Lea.) 



its structure the pancreas re- 

 sembles the salivary glands. It 

 consists of a connective-tissue 

 framework which divides the 

 gland tissue into lobules. Each 

 lobule is composed of a number 

 of acini or alveoli, more or less 

 elongated or tubular in shape. Each acinus gives origin to a small duct 

 which, uniting with adjoining ducts, forms the lobular duct, which becomes 

 tributary to the main duct. The acinus is lined by a layer of cylindric 

 epithelial cells characterized by a difference in structure between their cen- 

 tral and peripheral ends (Fig. 80). The central end, that bordering the 

 lumen of the acinus, is dark in appearance and filled with dark granules, 

 while the peripheral end is clear and homogeneous. The relative depth of 

 these two zones varies according to the functional activity of the gland. 



