4 o 



ELEMENTARY TISSUES. 



the usually more or less rounded outline of the cells com- 

 posing it (d, fig. 3), is found chiefly lining the interior of the 

 ducts of the compound glands, and more or less completely 

 filling the small sacculations or acini, in which they ter- 

 minate. It commonly indeed occupies the true secreting 

 parts of all glands, and hence is sometimes called glandular 

 epithelium (b, c, and<?, fig. 3) Often, from mutual pressure, 



the cells acquire a polygonal outline. From the fact, how- 

 ever, of the term spheroidal epithelium being a generic one 

 for almost all gland-cells, the shapes and sizes of the cells 

 composing this variety of epithelium are, as might be ex- 

 pected, very diverse in different parts of the body. 



(3.) The third variety is the cylindrical or columnar 



* Fig. 3. The gastric glands of the human stomach (magnified). 

 a, deep part of a pyloric gastric gland (from Kolliker) ; the cylindrical 

 epithelium is traceable to the csecal extremities, b and c cardiac 

 gastric glands (from Allen Thompson) ; #, vertical section of a small 

 portion of the mucous membrane with the glands magnified 30 diameters ; 

 c, deeper portion of one of the glands, magnified 65 diameters, showing 

 a slight division of the tubes, and a sacculated appearance produced by 

 the large glandular cells within them ; d, cellular elements of the cardiac 

 glands magnified 250 diameters. 



