7y2 



A MANUAL OF ANATOMY 



small intestine, and average about thirty in number in the adult, 

 being more numerous in early life. They are situated along the 

 free or anti-mesenteric border of the bowel, which must, therefore, 

 be opened along its attached or mesenteric border in order to 

 preserve them. They are largest, best marked, and most plentiful 

 in the lower half of the ileum. In the upper part of the ileum and 



Villus — 



Lieberkuhn's Crypt — '1^ 



Solitary Gland- . 



Muscularis Mucosae 



Submucosa— -5 



Circular Muscular Fibres 



Longitudinal 

 Muscular Fibres 



Mucosa 



Peritoneal Coat — - — —r. 



Fig. 340. — Vertical Transverse Section of the Small Intestine 

 (highly magnified). 



lower part of the jejunum they become smaller and more scarce, 

 and they disappear as a rule above the centre of the jejunum. 

 They vary in length from ^ inch to 4 inches, their breadth ranging 

 from I inch to i inch. They are for the most part oblong, their 

 long axis coinciding with that of the bowel. In the upper part 

 of the ileum and lower part of the jejunum, however, thev are 

 somewhat circular. Each patch is composed of a group of solitary 

 glands or lymphoid nodules, surrounded by lymphatic plexuses or 

 lymphatic sinuses. The area of each patch is slightly elevated, 

 and there are no villi over the lymphoid nodules, whilst the openings 

 of the crypts of Lieberkiihn are arranged in a circular manner 

 round each nodule. There are no valvulse conniventes over Peyer's 

 patches. The patches are best marked in young persons. Towards 

 middle life they fade away, and in old persons they are usually 

 only distinguishable as discoloured portions of the mucous 

 membrane. 



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