GLANDS OF THE ORAL CAVITY. 27 



powers, they all appear uniformly rounded or pyriform ; the 

 exact analysis of a whole lobe, or still better of a dissected and 

 injected gland, shows however, that their form is very various, 

 rounded, pyriform, or elongated. It is impossible to describe 

 at length all the forms which they assume ; I will therefore 

 only remark, that the ends of the glandular lobes frequently 

 repeat, on a small scale, the figure and structure of the seminal 

 vesicles, and refer to the subjoined diagrammatic figure. 



All the finest glandular ducts and vesicles, whose diameter 

 varies from 0*02 to 0-08'", consist of a peculiar, structureless 

 coat, the membrana 'propria, of 0-0008 — 0-0012'" in thickness, 

 and of an epithelium (fig. 180), which, in fresh preparations, 

 appears as a continuous investment of Fig. 180. 



the glandular extremities, but is very 

 readily detached, and then fills the glan- 

 dular vesicles as a granular mass. The 

 epithelial cells constitute a simple layer 

 upon the membrana propria, have 3 

 — 6 sides, are often somewhat elon- * 

 gated, 0-005— 0-006 /// broad, 0'003— 0-004'" thick, and in- 

 variably contain, besides a rounded or elongated nucleus of 

 0002 — 0-003'", often presenting a distinct nucleolus, a cer- 

 tain number of larger or smaller granules, which sometimes 

 simply resemble white fat, sometimes are coloured yellow- 

 ish and brownish, and contribute to the hue of the glands 

 themselves. 



The elements of the glandular lobes which have been just 

 described, though they are all applied very closely together, so, 

 indeed, as not uncommonly to be flattened against one another, 

 yet always present a small quantity of interposed connective 

 tissue, by which the vessels of the lobes are supported. Besides 

 this, the separate lobes and the entire glands are invested by 

 dense coats of a connective tissue, with elastic fibres, which 

 may, in addition, contain fat-cells. In small glands, such 

 as fig. 178, the only distinguishable subdivisions are the lobes, 

 glandular vesicles, and caeca, which have been described ; in 

 the larger, on the other hand, as in the glands of the lips 



Fig. 180. Two glandular vesicles of a racemose mucous gland of Man, x 300 : 

 a, membrana propria ; b, epithelium, as it appears in the apparent section of a 

 vesicle ; c, the same seen upon its surface. 



