MEMBRANES AND GLANDS. 103 



Structure, There is an investing capsule of fibrous connective 

 tissue which sends out septa into the substance of the gland; these 

 septa divide the gland into lobes and lobules. Each lobule is com- 

 posed of acini, each acinus consisting of a basement membrane lined 

 with secreting cells. The lumen of the acinus, or alveolus, leads to 

 the alveolar ductule, the ductules discharging into the salivary 

 tubes; the salivary tubes into the intermediate tubes; and these into 

 Stenson's duct, which is the large excretory duct. Stenson's duct is 

 composed of fibro-elastic tissue lined internally with a single layer 

 of columnar epithelium. 



Laboratory exercise No. 30. Parotid gland. Harden in alcohol, em- 

 bed in paraffin, and stain with carmine, method No. 3. It is well in 

 demonstrating- most structures to begin with the external, simpler 

 parts, and work inward to those that are more complex. In this case 

 demonstrate first the capsule and its penetrating 1 septa. Note how the 

 giand is diyided into lobes and lobules by the subdividing- septa. Ob- 

 serve an acinus, and note the form of the cell. Find Stenson's duct and 

 note its structure. Drawings. 



IV. THE PANCREAS. 



The pancreas is a compound tubular giand of the serous type. 

 The following outline exhibits its structure: 



OUTLINE OF THE PANCREAS. 



Capsule. 

 Septa. 



f Acini. 



Lobes < Gland cells. 



{ Bodies of Langerhans. 

 Pancreatic Duct. 



Intermediate tubules. 



Structure, The pancreas has the usual investing capsule of con- 

 nective tissue, from which extend numerous septa dividing the or- 

 gan into lobes. The lobes consist of acini, whose basement mem- 

 branes are lined with short cylindrical or conical cells. Each 

 cell is characterized by two zones a clear peripheral zone contain- 

 ing the nucleus, and the zone next the lumen which contains the 

 so-called zymogen granules. The bodies of Langerhans are imper- 



