SMALL INTESTINE. 



not been determined. Such cells, known as cells of Paneth, are invariably 

 present in the ileum, and often in the jejunum; they are not found in the 

 glands of the duodenum, or in those of the large intestine, with the possible 

 exception of the vermiform process. They are shown in Fig. 233. 



The sides of the glands are formed of columnar cells and goblet cells, 

 so arranged that the latter are seldom in contact with one another. It is 

 thought that any of the cells may elaborate mucus and become goblet cells, 

 in the manner described and figured on page 33. Mitotic figures are often 



Villi. 



x x 



Plica circularis. ' 



Intestinal glands. 



Submucosa. 



Circular muscle, 



Longitudinal g 

 muscle. 

 Serosa. 



FIG. 232. VERTICAL LONGITUDINAL SECTION OP THE JEJUNUM OF ADULT MAN. X 16. 



The plica circularis on the right supports two small solitary nodules, which do not extend into the sub- 

 mucosa; one of them exhibits a germinal center, x. The epithelium is slightly loosened from the 

 connective tissue core of many of the villi, so that a clear space, xr, exists between the two. The 

 isolated bodies lying near the villi (more numerous to the left of the plicae circulares) are partila 

 sections of villi that were bent, therefore not cut through their entire length. 



observed in the glands and seldom elsewhere. (In the stomach they occur 

 near the neck of the glands.) From this it is inferred that the outer cells, 

 including those of the villi, are replaced from below, and that the cells 

 toward the fundus of the glands are renewed from above. 



The epithelial cells of the villi are taller than in the glands, and the 

 goblet cells are somewhat larger. The columnar cells are covered by a 

 vertically striated top plate or cuticula, which is thinner in the outer part of 

 the glands and is absent from their deeper parts. The striation is con- 



