1640 



HUMAN ANATOMY. 



size, being sparingly present beyond the opening of the bile-duct and entirely want- 

 ing at the lower end of the duodenum. These glands are direct continuations of 

 the pyloric glands of the stomach, with which they agree in all essential details. 

 While, however, their gastric representatives are confined to the mucous coat, 



Fig. 1392. 



Solitary 

 nodule 



Fold 



Lymph- 

 nodules 



Surface views of mucous membrane from upper (A) and lower (B) part of ileum, showing folds and solitary lymph- 

 nodules. The velvety appearance is due to the villi. Natural size. 



Brunner's glands chiefly occupy the submucosa, the migration taking place at the 

 pyloric ring (Fig. 1391). The duodenum, therefore, possesses a double layer of true 

 glands, — those of Lieberkiihn within the mucous coat, beneath which, in the submu- 

 cosa, lie those of Brunner. The individual glands, tubo-alveolar in type, form some- 

 what flattened spherical or polygonal masses, measuring from .5-1 mm., which con- 

 sist of richly branched tubules, ending in dilatations. Their excretory ducts pierce 

 the mucous coat and open either directly on the free surface or into the crypts 

 of Lieberkiihn. While narrower than that of the alveoli, the epithelium of the 

 ducts is the same as that found in 



the deeper parts of the tubules. Fig. 1393. 



The clear, low columnar cells lining 

 the duodenal glands are proba- 

 bly identical in nature with those 

 of the pyloric glands, the varia- 

 tions in size and granularity some- 

 times observed depending upon 

 differences in functional condition. 

 Brunner's glands correspond to 

 the pure mficous tvpe (Bensley). 



Lymph - Nodules, — The 

 lymphatic tissue within the intesti- 

 nal tube occurs in the form of cir- 

 cumscribed nodules, which may 

 remain isolated, as the solitary nod- 

 Jiles, or be collected into consider- 

 able masses, as Peyer s patches. 



The solitary nodules vary 

 greatly in number and size, some- 

 times being present in profusion in all parts of the small intestine, at other times 

 almost wanting ; they are usually scanty in the upper and more numerous in the 

 middle and lower parts. They appear as small whitish elevations, spherical or pyri- 

 form in shape, and from . 2-2 or even 3 mm. in diameter, at the bottom of small pits. 



Solitary 

 nodule 



Villus 



Orifice of 



Lieberkiihn's 



gland 



Surface view of mucous membrane of ileum. X lO. 



