THE SMALL INTESTINE 



267 



FIG. 103 



extend to about one-half to two-thirds of the circum- 

 ference of the bowel. The villi in the mucous mem- 

 brane are described under absorption (see page 287). 



The Intestinal Glands or Glands of Lieberkuhn. These 

 are found in the mucous membrane throughout the 

 small intestines. They are minute tubular depressions 

 seen at the base of the villi and communicate with 

 the surface of the mucous 

 membrane, upon which they 

 pour out a special secretion 

 from the columnar cells which 

 line them; the latter rest on 

 a thin basement membrane, 

 which is surrounded by capil- 

 lary vessels. 



The Duodenal or Brunner's 

 Glands. They are found only 

 in the duodenum. They are 

 small, branched, tubular glands 

 situated in the submucouscoat 

 and open upon the mucous 

 membrane of the duodenum 

 by very small ducts. 



The Lymph Nodules. They 

 are divided into solitary fol- 

 licles and Peyer's patches. 

 Their bodies are in the sub- 

 mucous coat and their apices 

 in the mucous membrane. 



The solitary follicles are 

 found throughout the mucous 



and submucous layers of the small and large intes- 

 tines. They are small, round, whitish collections of 

 areolar tissue rich in leukocytes or white corpuscles, 

 and blood capillaries, and communicate through their 

 base with the lacteals of the villi. Each consists of 

 a lighter, central area, the germinal centre, where the 

 leukocytes are reproducing, and an outer darker zone, 



Intestinal gland in longitudinal 

 section. (Testut.) 



