THE DIGESTIVE TRACT. 



FIG- 



jacent gastric mucous membrane pass into the ducts of the glands 

 with little change, becoming imbricated, and, towards the neck, 

 shorter and more spherical in outline. At the 

 neck, the narrowest part of the tube, the cells 

 are more cuboidal, and assume a columnar or 

 pyramidal form as they approach the fundus. 

 The chief or central cells bound the lumen 



FIG. 196. 



Section of human stomach, showing general arrangement of its coats : 

 a, mucosa containing the tubular peptic glands ; e, muscularis 

 mucosae separating the layer of glands from the underlying submucous 

 coat (b) ; A, blood-vessels ; c, c", respectively the circular and longi- 

 tudinal muscular layers; d, the fibrous tunic covered with the peri- 

 toneum. 



Peptic gland from 

 stomach of dog: a, wide 

 mouth and duct which re- 

 ceive the terminal divisions 

 of the gland ; 6, c, neck 

 and fundus of the tubes ; e, 

 central or chief, d, parietal 

 or acid, cells. 



of the gland and form the bulk of the glandular epithelium. Each 

 cell contains a spherical nucleus embedded within the granular pro- 

 toplasm, whose exact condition depends upon the state of functional 

 activity. In addition to the chief or central cells, a second variety, 

 the parietal or acid cells, exists in the peptic glands. As indicated 

 by their name, the parietal cells are situated in the periphery of the 

 gland immediately beneath the basement-membrane, usually separated 

 from the lumen by the intervening central cells. Minute lateral 



