104 



HUMAN PHYSIOLOGY. 



and thus occupy the central portion of the gland, are termed central 

 cells. At irregular intervals, between the central cells and the wall 

 of the tubule, are found large, oval, reticulated cells, which, on ac- 

 count of their position, are termed parietal cells. (See Fig. 13.) 



FIG. 13. 



. Diagram showing the relation of the ultimate twigs of the blood-vessels, V. 

 and A, and of the absorbent radicles to the glands of the stomach and the 

 different kinds of epithelium viz., above cylindric cells; small, pale cells 

 in the lumen, outside which are the dark ovoid cells. (Yeo's "Text-book 

 of Physiology.") 



Each parietal cell is in relation with a system of fine canals, which 

 open directly into the lumen of the gland. It is estimated that the 

 fundus contains about five million glands. In the pyloric end of 

 the stomach the glands are generally branched at their lower ex- 

 tremities, and the common duct is long and wide. The duct is lined 

 by columnar epithelium, while the secreting part is lined by short, 

 slightly columnar, granular cells. The parietal cells are entirely 

 wanting. The epithelium covering the surface of the mucous mem- 

 brane is tall, narrow and cylindric in shape, and consists of mucus- 

 secreting goblet cells. The outer half of the cell contains a sub- 



