352 



THE DIGESTIVE SYSTEM 



The lining epithelium of the esophagus is of the stratified squamous 

 variety. Its attached surface is indented by the papilla? of the corium; 

 its free surface is smooth. In the collapsed state of the organ its mu- 

 cous membrane is thrown into longitudinal folds or rugae and its lumen 

 is largely obliterated. The small isolated areas of columnar or ciliated 

 epithelium, which occur in occasional individuals on the surface of the 

 esophageal mucosa, especially in its upper third, are to be regarded 

 as examples of irregular development, involving a persistence of the 

 ciliated areas occurring, according to Johnson (Amer. Jour. Anat., 10, 

 4, 1910), in embryos ranging from 55 millimeters to birth. 



THE STOMACH 



The Serous Coat (Tunica serosa). The serous coat of the stomach 

 is derived from the peritoneum. It is formed by a thin layer of sub- 



Lonyittidinal 

 section of glands 



Tunica propria 



FIG. 329. SECTION THROUGH THE STOMACH WALL OF MAN (PYLORIC REGION). X 14. 

 (Szymonowicz-MacCallum, "Histology and Microscopic Anatomy.") 



