STRUCTURE OF PEYER'S GLANDS. 



391 



stomach and are found throughout the whole intestine. They consist of small 

 masses of adenoid tissue loaded with leucocytes (Fig. 152). They are well supplied 

 with blood-vessels (p. 406), although no lymphatic vessels enter them. They are 

 surrounded by lymphatics, and, in fact, they may be said to hang into a lymph - 

 stream,] 



Diagram of a vertical section of the mucous membrane of the small intestine of a 

 dog, showing the closed follicles, a a ; b, muscularis mucosag. 



[Peyer's glands, or agminated glands, consist .of groups of lymph-follicles like 

 the foregoing (Fig. 153). 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 

 lymph-corpuscles often project between the epithelium. The 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 specially affected in typhoid fever.] 



Auerbach's plexus shown in section (human) a, ganglionic cells ; b, nerve fibres ; 

 c, section of the circular muscular fibres ; d, longitudinal muscular fibres. 



