THE SALIVARY GLANDS 



391 



or salivary ducts. The former are characterized by their very narrow 

 caliber and low epithelium. They are slender tubules which open on the 

 one side from the acini and on the other into the branched terminals of 

 the more spacious salivary ducts. The 'salivary* (secretory) portion of 

 the intralobular duct has a somewhat greater diameter also than the 

 excretory portion, which is histologically similar to the interlobular 

 ducts. In the parotid the salivary ducts are relatively short as com- 

 pared with the intermediate ducts, but are readily recognized by their 

 striated columnar epithelium, 

 which is deeply colored by acid 

 dyes (eosin, etc.), and are thus 

 sharply distinguished from the 

 secreting cells of the acini, 

 which stain poorly with these 

 dyes. 



The Submaxillary Gland. 

 In man and in most mam- 

 mals this organ is a mixed sal- 

 ivary gland; that of the bear 

 and dog contains the largest, 

 that of man and the apes the 

 smallest proportion of mucous 



acini (Krause, Arch. mikr. 



FIG. 362. FROM A SECTION OF THE HUMAN 



A nat., 1897). In man the SUBMAXILLARY GLAND. 



proportion of mucous to serous 

 alveoli is about one to five 

 (Piersol). The submaxillary 

 is situated in the floor of the 

 mouth under the posterior por- 

 tion of the mandible. The main submaxillary (Wharton's) duct opens 

 into the mouth one on either side of the frenulum of the tongue, some- 

 times joined by the duct of the sublingual gland. 



The serous acini of the- submaxillary are shorter and less typically 

 tubular than those of the parotid, and they are lined by taller secreting 

 cells. The diameter of the acinus is therefore slightly greater in this 

 gland than in the parotid. Its mucous acini contain a relatively large 

 proportion of demilunes. 



The intercalary ducts are considerably shorter than in the parotid, 

 while the salivary intralobular ducts are much longor in the submaxil- 

 lary. The interlobular connective tissue is not quite so delicate as in 



In the center is a small salivary duct, just 

 above which are three mucous acini, the 

 uppermost one possessing a demilune. The 

 other acini are serous. Hematein and eosin. 

 Photo. X 370. 



