438 



SPECIAL HISTOLOGY. 



Fi?.167. 



elastic element in the subcutaneous cellular tissue has generall}^ the form 

 of scattered, interstitial, and occasionally, though more rarely, of spi- 

 rally convoluted, fine fibres ; here and there, as in i\\Q frenulum epiglot- 

 tidis, they are not only more abundant, but thicker. The latter is inva- 

 riably the case in the proper mucous membrane, which, even close to the 

 epithelium, contains in the midst of its connective tissue, very close and 

 intimately connected networks of elastic fibrils, or (and this is the 

 general rule) of moderately thick elastic fibres of 0-001-0-0015 of a line. 

 Spirally convoluted elastic fibres exist here also, though rarely. In 

 addition, the mucous membrane contains common fat-cells, sometimes in 

 groups, sometimes more isolated, and especially in the submucous layer. 

 The vessels of the mucous membrane are very numerous, and present 

 essentially the same arrangement as in the skin. The smaller papilloe 



contain only a single capillary loop, 

 whilst in the larger, either simple or 

 branched, a network of capillaries 

 may be observed (Fig. 167) ; this is 

 especially the case in the gums, the 

 palate, the glandular region of the 

 root of the tongue, the lips, and the 

 lower surface of the tongue. The 

 investigation of the nerves presents 

 many difficulties. If caustic alkalies 

 be added, a wide network of the finer 

 and finest branches is rendered dis- 

 tinct in the outermost layers of the 

 mucous membrane, in which also, 

 divisions of the nervous fibrils may 

 be observed in some localities, par- 

 ticularly upon the anterior surface of the epiglottis ; on the other hand, 

 it is often impossible to detect so much as a trace of nerves in the 

 papilloe. Sometimes, however, even in these, especially in the larger, 

 one or two, often twisted, nerve-fibrils of 0-02 of a line in diameter, 

 diminishing to 0-0012 of a line, may be detected, without its being 

 possible to make out their ultimate destination ; upon the lip the papillce 

 possess axile-corpuscles similar to, but smaller than, those of the hand, 

 though not in all individuals. I found here, also, the nerve-coils 

 described by Gerber (see § 37). Of the origin and relation, in the 

 t. mucosa itself, of the abundant lymphatic vessels of the oral mucous 

 membrane, nothing is known. 



§ 130. The epithelium of the cavity of the mouth (Fig. 167), is a 

 ^o-GsWedi pavement epithelium, consisting of many superimposed layers 



Fig. 167. — A simple papilla with manifold vessels and epithelium, from the gum of a 

 jhild ; magnified 250 diameters. 



