rilK DinKSTIVK SYSTEM 



2(il 



as constituting the wall of the stomach, mucosa, submucosa, mnscii- 

 laris, and serosa. 



I. The mucosa, as in the stomach, is composed of a lining 

 epithelium, stroma, glands, and Diuscularis mucosce. Of these, the 

 epithehum, the stroma, and cells from the inuscularis mucosx-, are 

 concerned in the formation of the villi. 



The VILLUS consists of a central core — a fold of the stroma — of 

 mixed fibrous and reticular tissue infiltrated with lymphoid cells, and 

 of a covering epithelium. 



The epithelium is disposed in a single layer, separated from the 

 underlying connective tissue by a basement membrane. It consists of 



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^^j^^"^ 



_^&^ ^TS. 



Fig. 162. — Section through Junction of Pylorus and Duodenum. (Klein.) V, Villi 

 of duodenum; d, stomach, showing gastric pits; b, apex of a solitary lymph nodule; c, 

 crypt of Lieberkuhn; s, secreting tubules of Brunner'js glands; g, pyloric glands; t, 

 tubules of Brunner's glands in submucosa of stomach; m, muscularis mucosae. 



two apparently quite different kinds of cells, columnar cells Sind goblet or 

 mucous cells. The former are the more numerous and are pecuhar 

 to the intestine, while the mucous cells are identical with those found 

 in other mucous membranes. The columnar cells are quite elastic 

 and while .generally long and narrow, vary as to length and breadth 

 as they adapt themselves to movements of the intestine. Their pro- 

 toplasm is finely granular, its appearance depending somewhat on the 

 activity of secretion and absorption. It frequently contains fat 

 droplets. The nucleus is void and is usually situated in the basal third 



