THE STOMACH AND INTESTINE. 



271 



glands a condition probably due to the general absence of delo- 

 morphous cells. In the immediate vicinity of the gastroduodenal 

 valve the pyloric glands become shorter, and other glands, which 

 extend into the submucosa, and which are identical in structure 

 with the glands of Brunner in the duodenum, make their appear- 

 ance. In this portion of the pylorus are also a few scattered villi, 

 which from their structure may be considered as belonging to the 

 duodenum (yid. Fig. 218). 



In the normal condition the mucosa of the stomach contains 

 solitary lymph-nodules (lenticular glands) in the fundus region; 

 they are, however, more frequent in the pyloric region ; well-defined 

 lymph-nodules are constantly present in the immediate vicinity 

 of the pylorus. 



The muscularis mucosae is usually composed of three layers, 

 the fibers of the individual layers forming distinct interlacing bun- 

 dles. Individual muscle-fibers very frequently branch off from the 

 inner layer, assume a vertical position and disappear among the 

 glands. This arrangement is especially well seen in the muscularis 

 mucosae of the fundus of the stomach (Fig. 208). 



Only the inner and middle layers of the muscular coat of the 

 stomach enter into the 

 formation of the sphinc- 

 ter pylori (Fig. 2 1 8). 

 The fibers of the outer 

 layer, however, pene- 

 trate through the sphinc- 

 ter pylori and may even 

 be traced into the sub- 

 mucosa. When these 

 alone contract, the mus- 

 cular bundles of the 

 sphincter act somewhat 

 as pulleys, and a mod- 

 erate dilatation of the 

 lumen of the pylorus 

 is the result ( dilatator 

 pylori, Riidinger, 97 ). 

 (For further particulars about the stomach, compare Oppel, 96.) 



The changes which the epithelium and the secretory cells of the 

 stomach undergo during secretion are of special importance. These 

 relations have been carefully studied in animals by R. Heidenhain 

 (83). As far as our present knowledge goes, it would seem that the 

 same processes also occur in man. In a state of hunger the chief 

 cells of the fundus are large and contain numerous zymogen gran- 

 ules, while the parietal cells are small ; in certain cases the parietal 

 cells abandon their mural position and, like the chief cells, border 

 upon the lumen of the gland. During the first few hours of diges- 

 tion the chief cells remain large, while the parietal cells increase in 



Mucosa. 



Fig. 212. From section through human pylorus; 

 X6oo. 



