2O6 



HISTOLOGY. 



(Fig. 229), and beyond the duodenal papilla they are tall and close together. 

 They are also highly developed in most of the jejunum, but distally, as in 

 the ileum, they are lower and further apart. From the last two feet 

 of the ileum, they may be absent. As their name implies, they generally 

 tend to encircle the intestine. They may form short spirals, or branch and 

 connect with one another. Some of them are so oblique as to appear cut 

 transversely in cross sections of the intestine. 



Epithelium. 



Tunica 

 propria. 



Tunica 



propria. 



Muscularis ^jgs 



mucosae. 



Submucosa. Intestinal glands. Oblique sections of intestinal glands 



FIG. 231. VERTICAL SECTION OP THE Mucous MEMBRANE OF THE JEJUNUM OF ADULT MAN. X 80. 



The space, a, between the tunica propria and the epithelium of the villus is perhaps the result of the 

 shrinking action of the fixing fluid. At b the epithelium has been artificially ruptured. The goblet 

 cells have been drawn on one side of the villus on the right. 



There is only an arbitrary separation between the jejunum and the 

 ileum; the latter contains fewer and shorter villi, and its circular folds are 

 more widely separated. 



The entodermal epithelium of the small intestine is of the simple 

 columnar form and contains many goblet cells. Since that portion which 

 covers the villi contains perhaps as many goblet cells as the part which lines 

 the glands, it has been suggested that the latter are more properly termed 

 pits. At the base of the glands, however, there are often some cells con- 

 taining coarse granules, indicative of a special secretion. Its nature has 



