1294 



THE ORGANS OF DIGESTION 



possess villi on their free surface nor glands. Each patch is surrounded by a circle of the crypts, 

 of Lieberkuhn. They are best marked in the young subject, becoming indistinct in middle age, 

 and sometimes altogether disappearing in advanced life. They are largely supplied with blood^ 



...-Capillary network. 



FIG. 1022. Transverse section through the equatorial plane 

 of three of Peyer's follicles from the rabbit. 



FIG. 1023. Free surface of a Peyer's 

 patch. (After Quain.) 



vessels, which form an abundant plexus around each follicle and give off fine branches which 

 permeate the lymphoid tissue in the interior of the follicle. The lacteal plexuses which are 

 found throughout the small intestine are especially abundant around these patches; here they 

 form rich plexuses with sinuses around the glands (Fig. 1024). In typhoid fever there is ulcera- 

 tion of Peyer's patches. 



INTESTINAL VILLUS 



GLAND OF LIEBERKUHN 



CHYLIFEROUS 

 DUCT 



MIDDLE FOLUCULAH 

 ZONE 



INFERIOR LYM- 

 PHATIC PLEXUS 



FIG. 1024. Vertical cell of a Peyer's patch in a man with .the lymphatic vessels injected. (Frey 



Vessels and Nerves. -The arteries (vasa infestini tennis) are branches of the superior 

 mesenteric (Fig. 471) and course within the mesentery, forming single, double, or even tertiary 

 loops (Figs. 1025, 1026, 1027, 1028, 1029, and 1030). The terminal branches reach the intestine, 

 and each branch divides into two, one going to each side of the intestine and passing transversely 

 around it. At first they are directly beneath the peritoneum, but after a time they pass to the 



