

GLANDS OF THE ORAL CAVITY. 35 



The more intimate structure of the salivary glands presents 

 nothing remarkable. The glandular vesicles have about the 

 same diameter — 0*016 — 0*024 — 0*03'", in all three descrip- 

 tions of glands; they are as variously formed as in the mucous 

 glands, and proceed in a similar manner from the excretory 

 ducts. Their membrana propria frequently presents a double 

 contour, and is, internally, always clothed with a pavement 

 epithelium, whose cells of 0*005 — 0*008'" have a single nucleus, 

 and may be obtained in beautiful series by coarsely crushing 

 the gland; they are distinguished by their greater proportion 

 of fatty granules and pigment granules from those of most 

 mucous glands, whence the glandular vesicles themselves 

 present a somewhat dark appearance. Here, also, acetic acid 

 makes the contents of the cells turbid, the addition of an 

 excess even not restoring their clearness, and it is not therefore 

 advisable to make use of it in our examinations ; a very dilute 

 solution of caustic soda, which allows the epithelial cells to be 

 seen in situ, is more to be recommended. 



The excretory ducts of the salivary glands possess a single 

 layer of cylinder epithelium, whose cells measure 0*01 6'" in 

 length. The remaining portion of the wall, which is very 

 thick in Stenon's duct, but much thinner in the others, has a 

 dense, solid structure, and consists of connective tissue, with 

 a very close network of fine, and moderately thick, elastic 

 fibres. It is only in WTiarton's duct that we find, external to the 

 epithelium, and to a double layer of elastic membranes whose 

 elements are disposed transversely and longitudinally, a thin 

 stratum of smooth muscles, which, however, can only be 

 demonstrated and isolated with very great difficulty. They 

 are disposed longitudinally, have short nuclei of 0*004 — 

 0*006'", at most 0*008'", and are covered externally by a layer 

 of connective tissue with elastic fibres. 



The vessels of the salivary glands are very numerous, and 

 present the ordinary structure. The capillaries have a diameter 

 of 0003 — 0*004'", and form broad networks in which the 

 glandular vesicles are imbedded, so that each vesicle receives its 

 blood from several directions. A considerable number of ves- 

 sels are distributed also to the excretory ducts. Lymphatics are 

 found in the salivary glands, but their internal relations are un- 

 known. Nerves proceed from the plexus caroticus externus, with 



