66 PHYSIOLOGY FOR THE LABORATORY. 



III. THE MICROSCOPICAL STRUCTURE OF THE PAN- 



CREAS. 



Examine a cross-section of pancreas. 

 Observe : 



a. The arrangement of the cells in circular groups. Each 

 group is a cross-section of an alveolus, or tube formed by 

 secreting cells. 



b. A small opening, or duct, is in the centre of each alve- 

 olus, but is hardly visible, being filled by spindle-shaped 

 cells. 



c. The alveoli are grouped around larger ducts to form 

 lobules, which in turn unite to form the lobes of the pancreas. 



d. The lobes, the lobules, and the alveoli are bound 

 together by connective tissue carrying the blood-vessels. 



e. Sketch and label the various parts. 



IV. THE MICROSCOPICAL STRUCTURE OF THE LIVER. 

 Examine in the same way a cross-section of liver. 



Observe : 



a. The hepatic cells of which the liver is everywhere 

 composed. What parts of the cell can you distinguish? 

 How are they arranged? 



b. An hepatic veinlet is seen in section in the centre of 

 each group or lobule of hepatic cells. Whither does this 

 blood-vessel lead? 



c. Branches of the portal vein and hepatic artery may be 

 traced in the connective tissue between the lobules. 



d. The bile ducts are small tubes lined with a single 

 layer of cuboidal cells. What is their use? 



e. Sketch. 



