THE GASTRIC GLANDS. 525 



glands or tubuli, secrete the gastric juice; they are arranged, side by 

 side, in little groups (Fig. 94), perpendicularly to the surface of the 

 membrane, and form almost its entire substance. At the pyloric end 

 of the stomach, where the mucous membrane is thickest, the tubuli are 

 the longest, measuring nearly ^th of an inch in length; towards the 

 cardiac end, where the mucous membrane is thinnest, they are less 

 thickly set, and become gradually shorter, measuring only g^th of an 

 inch in length; their average diameter is about gg^th to sJ^th of an 

 inch, the orifices, c, being somewhat narrower. Each follicle is some- 

 what dilated, or flask shaped, at its deeper or blind end ; the larger 

 follicles are sometimes convoluted or varicose, and sacculated at the 

 blind end, or even subdivided into two, or sometimes, as in the pyloric 

 portion of the stomach, into as many as six or eight short sacculated 

 tubuli. These tubuli consist of extensions of the gastric mucous mem- 

 brane. The upper third of each tubule, next to its orifice, is lined by 

 columnar epithelial cells (Fig. 95, a), arranged perpendicularly on 

 the basement membrane. This epithelium is continuous with that at 

 the bottom of the alveoli, and on the interalveolar ridges, and indeed 

 is similar to that lining the stomach generally. In the lower two- 

 thirds of each tubule the epithelium changes its character, being com- 

 posed of soft, roundish, oval, or compressed nucleated cells, 5, which, 

 very much larger than the cylindrical epithelial cells, and distended 

 with granular matter, almost or completely block up the cavity of the 

 tubule. These soft epithelial cells are named the peptic cells, because 

 in or by them, the gastric juice, or, at least, its characteristic animal 

 substance, called pepsin, appears to be formed. Some of these cells 

 are present as microscopic elements of the gastric juice. The tubuli, 

 which are said to number about five millions, are sometimes named the 



Fig. 95. 



Jb: 



Fig. 95. Single gastric tubulus, or peptic gland, more highly magnified, a, neck of the tubule, lined 

 with columnar epithelium, b, dilated lower erd, or fundus, of the tubule, filled with oval nucleated 

 glandular epithelial cells, or peptic cells. Magnified 70 diameters. 



peptic glands. They are surrounded by a fine capillary network; 

 minute arteries and veins pass up and down between them, and end in 

 a capillary plexus on the bottom of the alveoli, and on the interalveolar 



