DIGESTIVE ORGANS AND THEIR ANATOMY. 



285 



the duodenum there are found additional glandular struc- 

 tures called the glands of Brunner. They are somewhat 

 longer tubular glands which extend down to the submucous 

 coat. The ducts of these open into the intestine between 

 the crypts of Lieberkuhn. The glands of Brunner have no 

 especial function, and are in all probability but glands 

 similar to the peptic glands of the stomach, which have 

 reached down into the commencement of the intestine. 

 They secrete small amounts of pepsin which, however, in 

 the intestine are of no value at all. We may therefore speak 

 of these glands of Brunner as ordinary gastric glands 

 which have been continued beyond the pyloric orifice. The 

 crypts of L,ieberkiihn are similar to the gastric glands, but 

 are much shallower and never possess added oxyntic cells. 

 Of course the secretion which they produce, the intestinal 

 juice, differs materially from the gastric juice. 



As the small intestine is to a much greater extent than 

 the stomach the seat of absorption, we find that the walls 



Fig. 115. SECTION OF AN INJECTED ILEUM, SHOWING THE INJECTED LACTEALS, VILLI, 



TWO PATCHES OF PEYER, ETC. (After Frey.) 



a, a, a, villi; 6, crypts of I,ieberkuhn; c, muscular layer of mucous membrane; d, d, 

 e, e, patches of Peyer; f, g, g, g' , networks of lacteals. 



are richly supplied with networks of blood-vessels and 

 lymphatics. Scattered very generally along the intestine in 



