306 



SPLANCHNOLOGY. 



by nuQierous 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 valvulce 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 Brunner. I Payer's patches. 



Crypts of Lieberkiihn. j 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 

 larger glands. 



The glands or patches of Ftyer, 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 vesi- 

 cular ductless sac, containing a lym- 

 phoid material. Single sacs, similar 

 to those forming Peyer's patches, 

 called solitary glands, are scattered 

 throughout the intestines, and sur- 

 rounded by LieberkUhn's crypts, 

 which form round each gland a ring 

 known as the corona tubulorum. 



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 gran- 

 ular 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 



ITlo. 101. 



"Section of mucous membrane of the small 

 Intestine. Ou the left a villus is seen in 

 section, a, The epithelial covering ; c, The 

 blood-vessels ; d, The basement membrane, 

 or subepithelial layer ; e, Spaces for re- 

 ception of the chyle ;/, Origin of a lacteal 

 vessel. On the right is a follicular depres- 

 sion in the mucous membrane, with b. The 

 cells lining it ; and c. The subepithelial 

 layer. 



