STKUCTUKE OF THE INTESTINES. 



1181 



become still smaller and more irregular, and, as a rule, they practically cease a 

 little below the middle of the ileum. 



Often patches of plicae circulares, much reduced in size, can be traced to within a short dis- 

 tance of the valvula coli. According to Sappey, Luschka, and others, they usually reach to 

 within two or three feet of the end of the ileum. 



Aggregated lymph 

 nodule 



Noduli Lymphatic! Solitarii. The solitary lymph nodules are minute masses of 

 lymph tissue, opaque and of a whitish colour, found 

 projecting on the surface of the mucous membrane TWO solitary glands 

 throughout the whole length of both the small and 

 large intestines. 



Isolated lymph cells are found in abundance 

 scattered through the connective- tissue layer of the 

 intestinal mucous membrane generally; in places 

 these cells are gathered together to form little nodules, 

 supported by a framework of retiform tissue, and sur- 

 rounded by a lymph space which communicates below 

 with the lymph vessels of the tela submucosa. Such a 

 collection of lymph cells constitutes a solitary nodule. 

 They are usually of a rounded or oval shape (Fig. 931), 

 the wide end resting in the tela submucosa, the nodule 

 itself piercing the lamina muscularis mucosse, and the 

 narrow end projecting slightly above the general sur- 

 face of the mucous membrane. In size they vary from 

 T ^th to Jth of an inch (*6 to 3'0 mm.), but their 

 average bulk is about that of a small grain of sago, to 

 which they bear some resemblance. 



As already mentioned, they are present throughout 

 the small and large intestines, being particularly 

 abundant in the vermiform process and the caecum. In 

 the small intestine they are found on the plicae cir- 

 culares, as well as upon the general surface of the solitary gland 

 mucous membrane between them. 



Noduli Lymphatici Aggregati. These lymph nodules 

 (O.T. Peyer's patches) consist of a large number of 

 minute lymph nodules grouped closely together so as 

 to form a slightly elevated area, usually of an oblong 

 form, on the surface of the mucous membrane (Fig. 

 931). In length they vary from half an inch (12 

 mm.), or less, to three or four inches (100 mm.), and 

 in width they commonly measure from a third to half an inch (8 to 12 mm.). 

 Their number is variable, buti in the average condition about 30 or 40 are found. 

 They are best marked in young subjects, where they form considerable elevations 

 above the general surface, and may be as many as 45 in number. After middle 

 life they atrophy, and in old age, although usually present, they are indis- 

 tinct, occasionally being marked by little more than a dark discoloration of the 

 mucous membrane. They are invariably situated along the surface of the intestine 

 opposite the line of mesenteric attachment, with their long axis corresponding to 

 that of the bowel. Consequently, in order to display them, the tube must be slit 

 up along its attached or mesenteric border. 



These aggregated nodules are entirely confined to the small intestine, being 

 largest and most numerous in the ileum, particularly in its inferior part, where 

 they usually assume an oblong shape; in the inferior half of the jejunum they 

 are small, circular, and few in number ; in its superior part they are rare ; and, 

 although their presence has been noted in the inferior portion of the duodenum, 

 they may be said to be absent, as a general rule, from this division of the intestine. 



Intermediate form 



FIG. 931. NODULI LTMPHATICI 

 AGGREGATI and SOLITAEII, 

 from intestine of child two years 

 old (natural size). 



Near the lower border are seen a 

 few small patches made up of 

 two or three lymph nodules ; 

 they are marked " intermediate 

 form." 



The plicae circulares stop at the margins of the 

 across them ; but villi are found on the surface of 

 the individual lymph nodules. 



nodules, and are not continued 

 nodules, in the intervals between 



