BRUNNER'S GLANDS. 



293 





fibres keep the lacteal open ; thus the parenchyma of the villus is also compressed transversely, 

 whereby the products of absorption are 

 forced into the lacteal. The muscles 

 are fixed by cement to the sub-epi- 

 thelial basal membrane. The muscu- 

 lar fibres of the villi are direct pro- 

 longations of the muscularis mucosa.] 



Nerves pass into the villi from Meiss- 

 ner's plexus lying in the sub-mucous 

 coat. The nerves to the villi are said < 

 to have small granular ganglionic cells' 

 in their course, and they terminate 

 partly in the muscular fibres and partly 

 in the arteries of the villi. 



[On making a vertical section of the 

 mucous membrane of the small in- 

 testine, it is seen to consist of a net- 

 work of adenoid tissue loaded with 

 leucocytes. This tissue forms its basis, 

 and in it are placed vertically side by 

 side, like test-tubes in a stand, im- 

 mense numbers of simple tubular 

 glands the crypts of Lieberkuhn (fig. 

 207).] [Kultschitzki finds that the 

 connective-tissue framework of the 

 mucous membrane of the small in- 

 testine is not true adenoid tissue, but 

 a transition form between the latter 

 and loose fibrous tissue.] Lieberkiihn's 

 glands open above at the bases of the 

 villi, while their closed lower extrem- 

 ity reaches almost to the muscularis 

 mucosa?. Each tube consists of a- base- 

 ment membrane lined by a single layer 

 of columnar epithelium, leaving a wide 

 lumen, the cells lining them being 

 continuous with those that cover the mucous membrane. Some goblet-cells are often found 

 between the columnar epi- Villi with blood-vessels injected. Solitary follicle. 



thelium. Immediately below 

 the bases of the follicles of 

 Lieberkuhn is the muscu- 

 laris mucosae, consisting of 

 two or three narrow layers of 

 non-striped muscular fibres 

 arranged circularly and 

 longitudinally. [It is con- 

 tinuous with the muscularis 

 mucosae of the stomach, and 

 extends throughout the 

 whole intestine, not as a con- 

 tinuous layer, but as a close 

 network of bundles of smooth 

 muscle. It sends fibres up- 

 wards into the villi (fig. 212, 



[Brunner's Glands are 

 compound tubular glands 

 lying in and confined to the 

 sub-mucous coat of the duo- 

 denum (fig. 198). Their 

 ducts perforate the muscu- 

 laris mucosa? to open on the 

 surface. They seem to be 

 the homologues of the py- 

 loric glands of the stomach.] 



[Solitary Follicles are small round or oval white masses of adenoid tissue, with their 

 deeper parts embedded in the sub-mucosa, and their apices projecting into the mucosa of the 



Fig. 210. * 



Mucous membrane of the small intestine of the dog ; 

 the lacteals are black, and the blood-vessels lighter. 

 a, artery ; b, lymphatic ; c, plexus of capillaries in the 

 villi ; d, lacteal ; e, Lieberkiihn's glands. 



Fig. 211. 

 Transverse section of duodenum of a rabbit injected, 



x-50. 



