306 



SPLANCHNOLOGY. 



by numerous minute villi and follicular openings, the whole 

 being clothed by columnar epithelium. It is thrown into folds 

 when empty, which usually disappear when it is dilated ; these 

 are known as valvuloB conniventes. 



INTESTINAL GLANDS. 



The mucous membrane of the small intestine is furnished with 

 glands and absorbents. Besides the mucous follicles, we note the 

 following glands : 



Glands of B runner. 

 Crypts of Lieberkiihn. 



Peyer's patches. 

 Solitary glands. 



The glands of Brunner, which are small glands, resembling 

 the acini of the salivary glands, are found in the duodenum. 



The crypts, or follicles of Lieberkuhn, are very small and are 

 found throughout the intestines, between the villi and around the 



O 



larger glands. 



The glands or patches of Peyer, are oval or circular groups of 

 solitary glands, forming agminated glands, and are found in the 



jejunum and ileum ; they are most 

 numerous near the termination of 

 the ileum. Each gland is a simple 

 vesicular ductless sac, containing a 

 lymphoid material. Single sacs, 

 similar to those forming Peyer's 

 patches, called solitary glands, are 

 scattered throughout the intestines, 

 and surrounded by Lieberkiihn's 

 crypts, which form round each gland 

 a ring known as the corona tubu- 

 lorum. 



The absorbents originate in the 

 villi, which are small, finger-like, 

 vascular processes, thickly distri- 

 buted over the mucous surface ; they 

 consist of loops of the lacteal or 

 chyle vessels, surrounded by a net-work of capillaries, fine muscular 

 fibres, and small granular corpuscles, with a mucous layer covered 

 by columnar epithelium. The small intestines are supplied with 

 blood by the anterior mesenteric and duodenal branch of the 

 hepatic arteries, the blood being returned by the satellite veins to 



FIG. 101. 



Section of mucous membrane of the 

 small intestine. On the left a villus is 

 seen in section, o, The epithelial cover- 

 ing ; c, The blood-vessels; d, The base- 

 ment membrane, or subepithelial layer ; e, 

 Spaces for reception of the chyle ; /, Ori- 

 gin of a lacteal vessel. On the right is a 

 follicular depression in the mucous 

 membrane, with 6, The cells lining it ; 

 and c, The subepithelial layer. 



