1 66 



NORMAL HISTOLOGY. 



FIG. 203. 



siderable latitude upon the underlying muscular tunic. The large 

 prominent folds, or rugae, of the stomach involve both the mucous 

 and the submucous coat, the latter forming the connective-tissue 

 frame-work of the elevation over which the mucosa with its glands 

 is reflected. Within the mesh-work of connective-tissue bundles 

 are supported the larger blood-vessels, lymphatics, and nerves. 



The muscular tunic comprises two principal sheets of involun- 

 tary muscle, disposed as an inner circular and an outer longitudinal 

 layer ; towards the cardiac end of the stomach irregular bundles of 

 oblique fibres constitute an imperfect third layer. The pyloric 

 orifice is guarded by a fold of mucous membrane supported by 

 the submucosa and strengthened by a conspicuous local annular 

 thickening of the inner circular layer of muscle ; the outer longi- 

 tudinal muscular layer and the serous coat pass over into the intes- 

 tinal wall without partici- 

 pating in the formation 

 of this gastro-duodenal 

 valve. 



The serous coat is 

 composed of bundles of 

 fibrous connective tissue, 

 together with rich net- 

 works of elastic fibres, 

 while the peritoneal sur- 

 face is covered with a 

 single layer of the charac- 

 teristic endothelial plates. 

 The narrow areas included 

 between the folds of the 

 peritoneum along their 

 lines of reflection are, of 



Section of injected stomach of cat : a, rugae consisting COUTSC, devoid of the 



of the mucosa and a core of submucous tissue (6) ; c, d, the cprons COVeHnP" ' at thpSP 

 circular and longitudinal layers of muscle ; all the dark 



lines represent the blood-vessels filled with the carmine- points the VCSScls and the 



gelatin mass ; the larger trunks break up in the submucosa, nerves DaSS tO and from 

 sending twigs into the mucous and muscular tunics. 



the stomach. 



The larger arteries, after penetrating the outer coats, divide 

 within the submucosa into smaller branches, one set of which pierces 

 the muscularis mucosae to be distributed to the mucous membrane, 

 while the other enters the muscular and serous tunics. The vessels 

 supplying the mucosa form a rich subepithelial capillary net- 

 work, as well as mesh-works surrounding the gastric glands, the cap- 

 illaries lying immediately beneath the basement in close proximity 

 to the glandular epithelium. The branches distributed to the outer 



