GLAXDS OF THE STOMACH. 



35a 



The mucous membrane is thickest in the pyloric region, and thinnest 

 in the great cul-de-sac. It always becomes thinner in old age. 



It is connected with the muscular coat by means of the intervening 

 subnuicous layer so loosely as to allow of considerable movement or 

 disphicement. In consequence of this, and of the want of elasticity of 

 the mucous membrane, the internal surflice of the stomach, when that 

 organ is in a contracted state, is thrown into numerous convoluted 

 ridges, r^/^ff, which are produced by the wrinkling of the mucous, 

 together with the areolar coat, and are entirely obliterated by disten- 

 sion of the stomach. These folds are most evident along the greater 

 curvature, and have a general longitudinal direction. 



On examining the gastric mucous membrane closely with the aid of 

 a simple lens, it is seen to be marked throughout, but more plainly 

 towards the pyloric extremity, with small depressions named alveoli," 

 Avhich have a polygonal figure, and vary from about y-^oth to y^o^h 

 of an inch across, being larger and more oblong near the pylorus. 



Towards the pyloric region of the stomach the margins of these 

 alveoli are elevated into pointed processes or fringes, which may be com- 

 pared to rudimentary villi, the perfect forms of those appendages ex- 

 isting only in the small intestine, and making their appearance in the 

 duodenum, immediately beyond the pylorus. 



The thick stratified epithelium of the 

 oesophagus passes abruptly at the cardia 

 into a simple layer of columnar epithe- 

 lium, which completely covers the inner 

 surface of the stomach, and extends to 

 a variable distance into the mouths of the 

 gastric glands. It agrees essentially with 

 the similar epithelium which covers the 

 intestine, and which will be afterwards 

 more particularly described. 



As first shown by Sprott Boyd, the 

 alveoli are dotted all over with small 

 round apertures, which are the mouths of 

 minute tubular glands {gasiric glands), 

 placed perpendicularly to the surface, 

 closed at their deep extremity, which ex- 

 tends almost to the submucous areolar 

 tissue, and opening at the other end on 

 the inner surface of the stomach. On 

 making a vertical section of the mem- 

 brane, and submitting it to microscopic 

 examination, it is seen to consist almost 

 entirely of these small iahiiU, arranged 

 close to and parallel with each other (fig. 

 247, a). Their diameter varies from -^^o 

 to iT6T)th of an inch, and their length 

 from -j-Lfh to ^^^^h of an inch. At the 

 cardiac end of the stomach, where the 

 membrane is thinnest, they are shorter, 

 and are for the most part simply tubular ; but, in approaching the pyloric 

 portion, they gradually become longer and assume a more complicated 



* The alveoli were termed " slomach-cells " by Boyd. 



Fig. 247. — Vertical Transverse 

 Skction op the Coats of a 

 Pig's Stomach. 30 Diameters 

 (from Kolliker). 



or, gastric glands ; h, muscu.ar 

 layer of the mucous membrane ; 

 c, submucous or areolar coat ; d, 

 circular muscular layer ; c, longi- 

 tudinal muscular layer ; /, serous 

 coat. 



