SEROUS ORAL GLANDS. 



i8 7 



the cells of the crescent are directly in contact with the lumen. Since the 

 serous crescents are always associated intimately and somewhat irregularly 

 with mucous cells, they were naturally interpreted as a functional phase 

 of the latter. It is probably true that some crescents represent empty 

 mucous cells which have been crowded from the lumen by those full of 

 secretion. No secretory capillaries lead to such mucous crescents, which 

 moreover are not abundant. Another sort of crescentic figure is made 

 by the basal protoplasm in mucous cells otherwise full of secretion. Fi- 

 nally, in oblique sections, stellate cells associated with the basement mem- 

 brane may resemble true crescents. 



The oral glands include serous 

 glands, mucous glands, and mixed glands 

 to be described in turn. "\ 1 /V^t^ i 



Serous Glands. 



The serous oral glands are the parot- 

 id glands and the serous glands of the 

 tongue [v. Ebner's glands]. The latter 

 are branched tubular glands limited to the 

 vicinity of the vallate and foliate papillae. 

 Generally they open into the grooves 

 which bound these papillae. Their ducts 

 are lined with simple or with stratified 

 epithelium, which is occasionally ciliated. 



Their Small tubules Consist Of a delicate FIG. 210. SECTION OF A SEROUS GLAND 



PROM THE TONGUE OP A MOUSE. X 240. 



rOpna Or basement mem- Prepared by Golgi's method, a precipitate 

 i i 111 t has formed in the ducts. The. right 



, Which SUrrOUndS the lOW Columnar lower part of the figure has beenlcom- 



. . pleted by adding the cell outlines. 



or conical serous cells. In this simple 



epithelium, cell walls are lacking. With special stains and high 

 magnification an outer dark granular zone has been distinguished from the 

 clear basal portion of the cell which contains the nucleus. The lumen of 

 the tubules is very narrow and receives the still narrower intercellular 

 secretory capillaries (Fig. 210). 



The parotid glands are the largest oral glands. Each is situated in 

 front of the ear and is folded around the ramus of the mandible; its duct, 

 the parotid duct [Stenson's], empties into the mouth opposite the second 

 molar tooth of the upper jaw. The parotid gland is an organic, branched 

 serous gland, subdivided into lobes and lobules. The accessory parotid 

 gland appears as a lobe separated from the others. The parotid duct is 

 characterized by a thick membrana propria and consists of a two layered 

 columnar epithelium with occasional goblet cells. As the duct branches 



