294 



SOLITARY FOLLICLES. 



intestine. They begin at the pyloric end of the stomach and are found throughout the whole 

 intestine. They consist of small masses of adenoid tissue loaded with leucocytes (fig. 214). 



They are . well supplied with 

 blood-vessels ( 197), although no 

 lymphatic vessels enter them. 

 They are surrounded by lym- 

 phatics, and, in fact, they may be 

 said to hang into a lymph-stream. 

 The distribution of solitary fol- 

 licles is fairly uniform in the 

 small intestine ; their number 

 generally increases from the 

 stomach to the large intestine ; 

 although there are considerable 

 variations in different individuals, 

 there seems to be the same num- 

 ber of solitary follicles and Peyer's 

 patches in the infant as in the 

 adult (Passov)).] 



[Peyer's glands, or agminated 

 glands, consist of groups of 

 lymph-follicles like the foregoing 

 (figs. 207, 213). The masses are 

 often more or less fused together, 

 their bases lie in the sub-mucosa, 

 while their summits project into 

 the mucosa, where they are 

 covered merely by the columnar 

 epithelium of the intestine. The 



Fig. 212. 

 Section of a solitary follicle of the small intestine (human), 



a, lymph-follicle covered with epithelium (6) which has lymph-corpuscles often pass be- 

 fallen from the villi", c; d, Lieberkiihn's follicle; e, mus- twee the epithelial cells. The 

 cularis mucosa? ; /, sub-mucous tissue. ' patches so formed have their long 



axis in the axis of the intestine, 

 and they are always placed opposite the attachment of the mesentery. Like the solitary glands, 

 they are well supplied with blood-vessels, while around them is a dense plexus of lymphatics 



or lacteals. They are 

 most abundant in the 

 lower part of the ileum. 

 These glands are speci- 

 ally affected in typhoid 

 fever. ] 



Nerves of the Intes- 

 tine. Throughout the 

 whole intestinal tract 

 there exists the plexus 

 of Auerbach, lying be- 

 tween the longitudinal 

 and circular muscular 

 coats (figs. 174, 175). 

 This plexus consists of 

 non-medullated nerves 

 with groups of ganglio- 

 nic cells at the nodes. 

 Fibres are given off by 

 it to the muscular coats. 

 Connected by branches 

 with the foregoing, and 

 lying iu the sub-mu- 

 cosa, is the plexus of 

 Meissner, . which is 



Fig. 213. 



Diagram of a vertical section of the mucous membrane of the small much finer, the meshes 

 intestine of a dog showing the closed follicles, aa j 6, muscularis being wider, the nodes 

 mucosa?. smaller, but also pro- 



vided with ganglionic 

 cells.- It supplies the muscular fibres and arteries of the mucosa, including those of the villi. 

 It also sends branches to Lieberkiihn's glands (fig. 176). 

 [Structure of the Large Intestine. It has four coats, like those of the small intestine. The 



