STRUCTURE OF SMALL INTESTINE. 



323 



Simple 

 tubes. 



They begin, as will be seen, in the duodenum, about one or two extent on 

 inches beyond the pylorus, and are continued in regular succession ^ e mtes - 

 to the middle of the jejunum ; but beyond that point they become 

 smaller and more distant from one another, and finally disappear 

 about the middle of the ileum, having previously become irregular 

 and rudimentary. The folds are largest and most uniform beyond, and 

 not far from the opening of the bile-duct By inspection of the dried 

 portion of the jejunum the disposition of these folds is readily seen. 

 GLANDS. In the glandular apparatus of the small intestine are 

 included the crypts of Lieberkiihn, solitary glands, and Peyer's 

 and Brunner's glands, the last-named 

 occurring only in the duodenum. 



The crypts of Lieberkiihn are minute 

 simple tubes, which exist throughout the 

 small intestine. They open on the sur- 

 face of the mucous membrane by small 

 orifices between the villi, and around 

 the larger glands ; but they are not to 

 be recognised with the naked eye. 



The so-called solitary glands (fig. 118, B) 

 are roundish white eminences, about the 

 size of mustard-seed if distended, which 

 are scattered along the small intestine, 

 but in greatest number in the ileum. 

 Placed on all parts of the intestine, and 

 even on or between the valvulae conni- 

 ventes, they are covered by the villi of 

 the mucous membrane, and are sur- 

 rounded at their circumference by aper- 

 tures of the crypts of Lieberkiihn. These 

 small bodies are nodules of lyniphoid 

 tissue. 



The agminated glands or glands of 

 Peyer (fig. 119) exist chiefly in the 

 ileum, and, beginning at the lower end, they should be looked 

 for by holding the bowel up against the light They form oval 

 patches, measuring from half an inch to two inches or more in size ; 

 length, and about half an inch in width. They are situate on the situation ; 

 part of the intestine opposite to the attachment of the mesentery, 

 and their direction is longitudinal in the gut : usually they are from 

 twenty to thirty in number. In the lower part of the ileum they number; 

 are largest and most numerous ; but they decrease in number and peculiari- 

 size upwards from that spot, till at the lower end of the jejunum ies * 

 they become irregular in form, and may consist only of small 

 roundish masses. The patches are most distinct in young persons, 

 and generally disappear in old age. 



The mucous membrane over the glands is hollowed into pits 

 (fig. 119, 6), and is generally destitute of villi (fig. 118, A) ; but 

 between the pits it has the same characters as in other parts. 



T 2 



FIG. 119. PETER'S PATCH, 

 FOUR TIMES ENLARGED 



(K6LLIKER). 



a. Surface of mucous mem- 

 brane covered with villi. 



b. Pits over the follicles 

 where villi are absent. 



Patches of 

 Peyer : 



