i88 



ELEMENTS OF HISTOLOGY. [Chap. xxm. 



in the smaller ducts ; in mammals, the epithelium 

 is a single layer of polyhedral cells. No fibrillation 

 is noticeable in the epithelial cells. At the transition 

 of the terminal ducts into the alveoli there is occasion- 

 ally a slight enlargement, called the infundibulum ; 



here the granular- 

 looking epithelial 

 cells of the duct 

 change into the 

 columnar transparent 

 mucous cells lining 

 the alveoli. 



252. The alveoli 

 of these glands are 

 identical with those 

 of the mucous glands 

 described above (Fig. 

 110) e.g., the sub- 

 lingual gland, as re- 

 gards size, tubular 

 branched nature, the 

 lining epithelium, and 

 lumen. 



In some instances 

 (as in the soft palate 

 and tongue) the duct 

 near the opening is 

 lined with ciliated 

 columnar epithelium. 

 The stratified epithe- 

 lium of the surface is generally continued a short dis- 

 tance into the mouth of the duct. 



253. The serous glands at the root of the 

 tongue (von Ebner) differ from the mucous chiefly 

 in the size, epithelium, and lumen of the alveoli. 

 These are of exactly the same nature and structure 

 as those of the serous or true salivary glands. 



Fig. 110. Part of a Lobule of a Mucous 

 Gland in the Tongue of Dog. 



o, Gland tubes (alveoli) viewed in various 

 directions ; they are lined with transparent 

 ' mucous cells;" d, duct, lined with small 

 polyhedral cells. (Atlas.) 



