1026 



THE ORGANS OF DIGESTION. 



outer boundary. The surface of a patch is usually free from villi; it is surrounded 

 by a row of the crypts of Lieberkiihn. They are best marked in young subjects, 



where as many as 45 have been observed ; 

 they become indistinct in middle life and 

 ...-Capillary network, even disappear in old age. Their resem- 

 blance to lymph-glands is seen in any in- 

 fectious disease of the intestines, especially 

 in typhoid fever, where they may ulcerate 

 and perforate to the peritoneal cavity, 

 causing fatal haemorrhage. 



They have a large vascular supply 

 which forms an abundant plexus around 

 each follicle. This gives off fine capil- 

 laries, which, supported by the retiform 

 tissue, converge toward the centre (Fig. 

 647). The lacteal plexuses, which are 

 abundant throughout the small intestine, 

 are especially so around the follicles of a 

 Peyer's patch, often forming sinuses 

 around them (Fig. 648), 



Resume. The valvulge conniventes 

 and villi are most abundant in the upper 

 part of the small intestine. 



Brunner's glands are mostly in the 

 duodenum. 



Solitary glands and Peyer's patches are most abundant in the lower part of 

 the small intestine. 



The crypts of Lieberkiihn are abundant in both large and small intestines. 

 The large intestine possesses the crypts of Lieberkiihn and solitary glands. 



FIG. 647. Transverse section through the equato- 

 rial plane of three of Peyer's follicles from the rabbit. 



FIG 648 Vertical section of one of Peyer's patches from man, injected through its lymphatic canals, a. 

 Villi with their chyle-passages, b. Follicles of Lieberkiihn. c. Muscular mucosse. rf. Cupola or apex of solitary 

 glands e Mesial zone of glands. /. Base of glands, g. Points of exit of the chyle-passages from the villi, and 

 entrance into the true mucous membrane, h. Eetiform arrangement of the lymphatics in the mesial zone. i. 

 Course of the latter at the base of the glands, k. Confluence of the lymphatics opening into the vessels of the 

 submucous tissue. I. Follicular tissue of the latter. 



Vessels and Nerves of the Small Intestine. 



The arteries supplying the duodenum are the pyloric, the superior pancreatico- 

 duodenal, from the gastro-duodenal, all of which come from the hepatic, and the 

 inferior pancreatico-duodenal, from the superior mesenteric. 



The jejunum and. ileum are supplied by the superior mesenteric artery, the 



