72 ALIMENTARY CANAL. 



Pyloro duodenal junction. Y.L.S. Cat. (p. 3, inj., &c., the same 

 as the last.) (L) Follow the surface of the mucosa from the 

 pyloric side, and observe that the transition to duodenum is 

 marked by the gradual appearance of projections (villi) in the 

 spaces which correspond to the intervals between the ducts of 

 the gastric glands. The mucosa is apparently increased in thick- 

 ness ; this is, however, due to the compact mass of glandular 

 tissue (Brunner's glands) in the sub-mucosa, which may at first 

 be taken as part of the mucosa until the position of the muse, 

 mucosae is recognised. The villi are column-like projections from 

 the mucosa proper. In the latter, recognise the glands of 

 Lieberkiihn, which open on the surface between the villi. They 

 are simple tubular glands. The muscular coat of the stomach 

 undergoes a sudden and great increase to form the pyloric ring, 

 which diminishes as rapidly on the duodenal side and there 

 presents two regularly disposed layers. In the duodenum lymph 

 nodules are met with in the sub-mucosa. Their dome-like pro- 

 jections penetrate to the free surface of the mucosa. (See 

 Peyer's patch later.) 



(H) Examine: The nmcosal transition; the villi; the 

 openings of the Lieberkiihn's glands on the surface, and the 

 epithelium which lines them ; also the ducts and secreting acini 

 of Brunner's glands, the epithelium of which resembles that in 

 mucous glands ; the muscular coat and Auerbach's plexus. 



Injected stomach. "V.S. Fundus of cat's stomach. (Carmine 

 gelatin mass, p. 2 (d), s. 22, c. P. or G., m. F. or B.) Follow the 

 large blood vessels from the sub-mucosa to their branchings 

 in the mucosa. The arteries penetrate nearly to the surface 

 before dividing, and then sub-divide into a capillary network 

 which forms a return system through the mucous membrane 

 around the glands to converge into a system of veins which 

 debouch into the sub-mucosa. The arteries are terminal, e.g., 

 have no free anastomoses. 



