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TEXT-BOOK OF PHYSIOLOGY 



tion to the chief cells, the cardiac glands contain a second variety of cell, 

 which is of a larger size, of a triangular or oval shape, and consisting of a 

 finely granular protoplasm. From their situation in and just beneath the 

 gland wall they have been termed parietal or border cells. Each parietal 

 cell appears to be surrounded and penetrated by a system of passages which 

 open into the lumen of the gland by means of a delicate cleft or canaliculus 

 (Fig. 73). Glands with these histologic features are most abundant in the 

 middle zone of the stomach. 



The pyloric glands are also formed by an involution of the mucous mem- 

 brane and lined by epithelial cells (Fig. 74). The ducts are much longer 

 than the ducts of the cardiac glands. At its ex- 

 tremity each duct becomes branched, giving rise to a 

 number, from 2 to 10, of short tubes, each of which 

 has a large lumen and communicates with the duct by 

 a narrow short neck. The ducts are lined through- 

 out by columnar epithelium. According to Mall, the 

 total number of openings on the surface of the mucous 

 membrane of the dog's stomach is somewhat over 

 1,000,000, and the total number of blind tubes opposite 

 the muscularis mucosae exceeds 16,500,000. Accord.- 

 ing to Sappey, the surface of the mucous membrane 

 of the human stomach presents over 5,000,000 orifices 

 of gastric glands. 



FIG. 72. CARDIAC GLAND. 

 m Mouth of the duct; n, neck; 

 /. fundus; c, central cells; 

 p, parietal cells. (Landois 

 and Stirling.) 



Lumen. 



Secretor 

 capillaries. 



FIG. 73. SECTION OF CARDIAC GLAND 

 Oi MOUSE. Left upper half drawn after 

 an alcohol preparation, right upper half 

 after a Golgi preparation. The entire 

 lower portion is a diagrammatic combi- 

 nation of both preparations. (Stdhr.) 



Blood-vessels and Nerves. The blood-vessels of the stomach after 

 entering the mucosa break up into a number of branches which are dis- 

 tributed to the muscle and mucous coats. The branches to the latter soon 

 form a capillary network with oblong meshes which not only surround the 

 tubules but form a network just beneath the surface of the mucosa. Veins 

 gradually arise from the capillaries which empty into the larger veins of the 

 mucosa. The glands are also supported by processes of smooth muscle- 

 fibers passing up from the muscularis mucosae. 



The nerve elements are partly intrinsic and partly extrinsic. The in- 



