33* 



PEYER S PATCHES. 



[sect. 155. 



The most important of them are the collections or patches ofPeyer 

 (glandulce Peyeriance sive agminatai). They mostly occur in form of 

 Fig. 142. oblong or roundish flattened organs, 



which are arranged in thelongitudinal 

 direction, invariably on the border 

 of the intestine opposite to the at- 

 tachment of the mesentery. They 

 are best seen from within, and 

 appear as not very distinctly cir- 

 cumscribed, slightly depressed and 

 smooth patches. But even from 

 without they may be recognised, by 

 a slight elevation of the intestinal 

 wall, and, by transmitted light, look 

 like opaque parts of the membrane. 

 The seat of these collections is, in most 

 cases, the ileum ; still they are not 

 unfrequently met with in the lower 

 part of the jejunum, occasionally in 

 its upper half near to the duodenum, 

 and even in the horizontal inferior 

 part of the duodenum. In ordinary 

 cases, their number is 20 to 30 ; when 

 they are met with also higher up 

 they increase to 50 or 60; but they are always most close to one 

 another in the lowest part of the ileum. The size of the 

 patches is usually larger the nearer they are to the ececum ; and 

 their length mostly amounts to from 5'" to 1^ in., but may be 

 only 3'", or increase to 3 or 5 in., or even 1 ft., whilst their 

 breadth measures 3'", 5"' to 9'". The folds of Kerkrlng are usually 

 interrupted wherever Peyerian patches are situated ; still, in the 

 jejunum, folds are found also upon the patches, and, in the ileum, 

 instead of them, frequently rows of closely set villi. When more 

 narrowly examined, each Peyerian collection is found to be an 

 aggregation of closed follicles, which have a roundish shape, or 

 are somewhat conical and tapering towards the cavity of the 

 intestine, -*-'" to \'" to 1'" in size. The follicles lie close to each 

 other, have their seat partly in the mucous membrane itself, 

 partly in the submucous tissue, and, on the one side, are distant 

 only o - 02'" to 003" from the surface of the mucous membrane; 

 whilst, on the other, they immediately adjoin the muscular coat, 



A human Peyerian collection ; magni- 

 fied 4 times, a. Surface of the ordinary 

 mucous membrane, with villi ; b. depres- 

 sions upon the patch corresponding to the 

 follicles ; c. intermediate substance with 

 small villi. 



