THE SUBMAXILLARY GLAND. 



149 



The Submaxillary Gland. This organ, intermediate in size between 

 the parotid and sublingual glands, lies largely under cover of the lower jaw, 

 invested by a fibrous capsule derived from the cervical fascia. It consists of 

 two parts, the superficial, resting on the outer surface of the mylo-hyoid 

 muscle, and the deeper, which winds around the posterior border of the last 

 named muscle and extends forwards as a tongue-like process, between the 

 mylo-hyoid and the hyo-glossus muscles almost as far as the sublingual 

 gland, beneath the mucous membrane of the floor of the mouth. 



The submaxillary gland differs in structure from the parotid in possessing 

 both serous and mucous alveoli, the mucous forming approximately one fifth 

 of the entire gland-tissue. The alveoli containing serous cells resemble 

 those of the parotid, during rest being filled with cells loaded with minute 



Duct 



Mucous alveoli 





Serous alveoli 

 FIG. 189. Section of submaxillary gland, showing serous and mucous alveoli. X 270. 



secretion granules. These cells often exhibit a differentiation into an inner 

 granular and an outer almost granule-free zone. The mucous alveoli are 

 somewhat larger than the serous ones and contain chiefly mucus-secreting 

 cells, although limited groups of serous cells are present as demilunes. 

 Intermediate tubules connect alveoli of both kinds with the intralobular 

 ducts, those from the mucous alveoli being shorter and less branched than 

 those from the serous acini. The latter are lined with low cuboidal cells, 

 which pass gradually into the gland-cells of the alveoli, in contrast to the 

 abrupt transition in the tubules leading to the mucous acini. The cells lin- 

 ing the intralobular ducts exhibit the striation seen in the corresponding 

 part of the parotid, this rod-epithelium sometimes containing yellowish pig- 

 ment. The interlobular and interlobar ducts resemble those of the parotid 

 gland. The main excretory or Whartori s duct possesses, in addition to its 

 fibrous tissue and a subepithelial layer of elastic fibres, feebly developed 

 bundles of longitudinally disposed unstriped muscle. Goblet-cells appear 

 among the columnar epithelium lining the deeper parts of the duct. 



The Sublingual Gland. This, the smallest of the salivary glands, 

 underlies the mucous membrane of the floor of the mouth, through which it 

 shows as an oval elevation at the side of the median fold, the frenulum. The 



