SALIVARY GLANDS. 255 



SALIVARY GLANDS. 



The Parotid Gland (Serous Gland). The parotid glands may 

 be classed as compound branched alveolar glands. The gland is 

 made up of distinct lobes and lobules. The secreting compart- 

 ments consist of irregular, convoluted tubules, which are joined by 

 a narrow intermediate duct to the intralobular ducts. The epithe- 

 lial cells lining the acini of this gland are short, irregularly colum- 

 nar or cubic cells, with round or oval nuclei, situated nearer the 

 basal portions of the cells, the protoplasm presenting different 



Acini. 



Fig. 198. Section through salivary gland of rabbit, with injected blood-vessels ; X 7- 



appearances according to their physiologic condition. When at 

 rest, the cells are filled with fine granules, which are to be regarded 

 as consisting of a substance from which the specific secretion is 

 formed, a substance known as zymogen, the granules being known 

 as zymogen granules. These granules are in the paraplasm of the 

 cells, from which they are probably developed. As secretion pro- 

 ceeds the outer portion of the cell becomes free from granules, these 

 being used up in the formation of the secretion (Langley). 



The Sublingual Gland (Mucous Gland). The sublingual 

 glands are compound branched tubulo-alveolar glands. These 



