GLANDS OF THE ORAL CAVITY. 



521 



Each of these organs is an aggre- 



Fig. 350. 



Vessels of a few follicles from a human tonsil, 

 seen from the cavity of a sac. Magnified 60 diame- 

 ters. (Kolliker.) 



though found in the pharynx, 

 gation of 10 to 20 compound 

 follicular glands, held together 

 by a common investment, and 

 forming a hemispherical mass. 

 The apertures of the follicles 

 frequently unite so as ulti- 

 mately to form only a small 

 number on the surface. The 

 structure of the tonsil is, there- 

 fore, understood from the pre- 

 vious description of the sim- 

 ple follicular glands. It should 

 also be added, that the tonsils 

 receive the ducts of mucous 

 glands. The vessels distri- 

 buted to the closed capsules 



are more numerous than those of the lingual follicles. (Fig. 350.) 

 Nerves exist on the surface of the tonsil and in the papilla; but 

 have not been found in the membrane of the closed capsules. 



What the precise function of the closed capsules is, is not deter- 

 mined. But at least their contents are very similar to those in the 

 follicular cavity around which they lie, though no capsules are 

 found burst. 



3. The salivary glands (parotid, submaxillary and sublingual), 

 may be regarded as compound racemose mucous glands, so far as 

 their structure is concerned; their primary lobules corresponding 

 to those of a mucous gland, and their secondary to the entire rnu- 

 cous gland. (Fig. 348). These last are united into larger lobes, and 

 thus the whole salivary gland is made up. (Fig. 316, c.) 



The excretory ducts of the salivary glands have a conoidal epi- 

 thelium consisting of a single layer of cells 7 J^ of an inch long. 

 The remainder of their wall (very thick in Stenon's duct), is a firm 

 and condensed layer of areolar tissue. In Wharton's duct, there is 

 a thin layer of smooth muscular fibres within the areolar tissue; 

 while there is also a double elastic layer between this muscular 

 layer and the epithelium. The vessels are abundantly distributed 

 to the primary lobules, as to those of the mucous glands; the capil- 

 laries being 7 oW to 3 oV<y of an mc ^ i n diameter. Lymphatics are 

 also found in the salivary glands. Nerves proceed into them also, 





