THE DKiESTIVE SYSTEM 



253 



with its elevations and depressions. In the deeper structures the Hne 

 of demarcation is not so abrupt, the muscularis mucosae of the oesoph- 

 agus being continuous with that of the stomach, and glands of the 

 stomach type extending up under the stratified epithelium of the 

 oesophagus (Fig. 153). 



I . The mucous membrane of the stomach is folded into ridges or 

 rugos, the height and number of which depend, as already noted, upon 

 the degree of distention of the organ. The rugae are most prominent 



Fig. 1 54. — Outline Diagram of Stomach to showLocation of Different Kinds of Glands. 



■c, cardia; p, pylorus; vvvvvv, cardiac glands; , fundus glands; + + + + + , pyloric 



glands; oooooo, intestinal type glands (of Lieberkuhn). (Jouvenal.) 



in the collapsed organ, almost absent when the organ is fully dis- 

 tended. In addition to the rugae the entire mucous membrane is 

 studded with minute depressions barely visible to the naked eye, the 

 so-called gastric pits (Fig. 156, Mg). These mark the openings of the 

 gastric glands. In the fundus they are comparatively shallow, ex- 

 tending through about one-fifth the thickness of the mucosa; in the 

 pylorus the pits are much deeper, extending through half or more of 

 the thickness of the mucous membrane (compare Figs. 156 and 160). 

 The Epithelium. — This is of the simple columnar type, covers the 

 entire surface of the gastric mucosa and extends down into the pits 

 (Fig. 156). The cells are of the high, clear, mucous type (Fig. 157, 

 M and M'). The end of the cell toward the lumen is clear, usually 

 consists mostly of mucus, and consequently stains lightly. There 



