PETER'S PATCHES. 



365 



Fi?. 261. 



^^PPS 



m 



most jooints distinctly marked olf from it, partly owing to the fact that 

 their supporting retiform tissue becomes closer and finer, partly owing 

 to their being closely surronnded by a rich plexus of ]ymi)hatic vessels ; 

 or they may even hang, as it were, into a lymph (or lacteal) sinus, which 

 entirely surrounds the follicle, except above. The epithelium over 

 the follicles often shows a large number of lymph corpuscles between 

 the epithelial cells. The main part of the follicle is situated in the 

 submucoas tissue ; but it extends upwards, piercing the muscularis 

 mucosa, into the mucous membrane, causing a slight bulging of this 

 towards the interior of the gut (as in fig. 2G4, d d). The prominent 

 part of the follicle has villi "upon it, and, placed around very irregu- 

 larl}', are seen the mouths of the crypts 

 of Lieberkiihn (fig. 260). 



Tlie agminatsd glands or glands of 

 Peyer (who described them in 1G77), 

 are groups or patches of lym])hoid follicles. 

 The groups have an oblong figure (fig. 2G1), 

 and vary fi-om half an inch to two or even 

 four inches in length, being about half an 

 inch, or rather more, in width : they arc 

 placed lengthways in the intestine at that 

 part of the tube most distant from the 

 mesentery ; and hence, to obtain the 

 best view of them, the bowel should be 

 opened by an incision along its attached 

 border. 



The lymphoid nodules (fig. 264) which 

 by their aggregation make up a Peyer's 

 patch are in almost all respects similar to 

 the solitary glands above described. As 

 a rule, however, their surface is free from 

 villi, and the crypts of Lieberkiihn are col- 

 lected in circles around the follicles (fig. 

 262). In the situation of Peyer's patches, 

 the mucous and submucous coats of the 

 intestine adhere more closely together 

 than elsewhere, so that it is there im- 

 impossible to inflate the areolar coat. 

 Fine blood-vessels are distributed abundantly on the exterior of the 

 follicles, and give ofi:' still finer capillary branches, which, supported by 



>1. — A Small I'ati h of 

 Peyer's Glands from tiieIleuji. 

 Slightly JrAGNiFiED (Pcelim.) 



Fig. 262. — Enlarged Yitay of a part of a 

 Patch op Peyer's Glands, showing four 

 Follicles. Magnified about 10 Diameters. 



The figure shows the surface of the intestinal 

 mucous membrane over part of a patch, occupied 

 by villi, between which are the orifices of the 

 crypts of Lieberkuhn ; except over the four folli- 

 cles, where there are no villi. The crypts of 

 Lieberkiihn are arranged chiefly in circles round 

 the nodules. 



Fig. 262. 





the retiform tissue, are disposed principally in lines convergino- to the 

 centre (fig. 263). 



