ABDOMINAL CAVITY 355 



surface is observed to present a pitted appearance. In- 

 numerable polygonal depressions are brought into view; 

 they are larger and better marked near the pylorus than 

 in the vicinity of the fundus. At the bottom of the de- 

 pressions are the mouths of the minute tubular glands of 

 the gastric mucous membrane (Fig. 165). 



The mucous membrane has little elasticity, and, con- 

 sequently, when the stomach contracts and becomes empty 

 the membrane is thrown into projecting folds or rugae which, 

 for the most part, run in the longitudinal direction and 



Mouths of 

 gastric glands, 

 with gland 

 tubes at tf 

 bottom f 



Depression 



between two 



mamillae 



Mouth of 

 gastric gland "jT 



I '!<;. 165. Mucous Membrane of the Stomach magnified 25 diameters. 



occupy the cavity of the organ (Figs. 164, 166). As the 

 stomach expands the folds open out, and they disappear 

 when complete distension is attained. 



Dissection. Extend the incision already made in the second 

 part of the duodenum upwards into the first part, to within a 

 short distance of the pyloric constriction, and examine the 

 pyloric orifice and the pyloric canal. 



Pyloric Orifice and Pyloric Canal. The extremity of the 

 pyloric canal protrudes into the commencement of the 

 duodenum, so that, when viewed from the duodenal side, it 

 presents the appearance of a smooth, rounded knob, sur- 

 rounded by a shallow furrow or fornix, and having a small 

 puckered orifice, the pyloric opening, in its centre (Fig. 167). 

 Its resemblance to the external orifice of the uterus is very 

 striking. When the stomach has been properly hardened in 

 situ the pyloric orifice is almost invariably found tightly closed. 

 It is only on rare occasions that it is actually open. In 

 such cases it is circular, and surrounded by a ring-like ledge 

 which has been called the pyloric valve. During life the 

 pyloric opening may be regarded as being always rigidly 



