296 



THE DIGESTIVE SYSTEM 



\- I 



branch and pursue a somewhat tortuous course to the fund us of 



the gland, where the terminal 

 acini of each subdivision of 

 the duct are invested with a 

 a distinct fibrous capsule. 



The secreting epithelium 

 of Brunner's glands consists of 

 tall columnar cells which sur- 

 round a wide lumen. When 

 loaded with secretion the cells 

 are swollen and clear, but be- 

 come shrunken and granular 

 after a period of activity. 

 Their cytoplasm reacts to the 

 specific stains for mucin only 

 when these are applied for a 

 considerable time in concen- 

 trated solutions (Bensley). 

 The spheroidal nucleus is situ- 

 ated at its proximal or basal 

 end and as the cell fills with 

 secretion the nucleus becomes 

 progressively flattened. 



BLOOD SUPPLY. The 

 blood supply of the small in- 

 testine resembles that of the 

 stomach. The branches of 

 the mesenteric arteries pass 

 around the intestinal wall in 

 the subserous connective tis- 

 sue. From this~ point they 



FIG. 242. THE BLOOD VESSELS OF THE SMALL J 



INTESTINE OF A DOG, DRAWN AFTER AN penetrate the muscular coat to 

 INJECTED PREPARATION. form intramuscular and sub- 



The arteries are striped, the veins black, niUCOUS plexuses. From the 



the capillaries open. A, villi; B, crypts; , , , i 



<?, muscularis mucosse; D, submucosa; E, latter a few Branches Supply 



circular, and F, longitudinal layer of the the adjacent portion of the 



muscular coat; a, venule beginning from the inner layer of the muscu l ar 

 capillaries of the villus, and at 5, from those , <> i 



among the crypts ; c, artery to the villus ; d, coat bufc most oi them pass 



venules in the deeper part of the mucosa; <?, to the H1UCOUS membrane, in 



main arterial trunk to several adjacent villi ; ^ h lexu j. . t 

 ar " J 





/, arterial branch to the glandular region. 



Highly magnified. (After Mall, from Oppel.) the niUSCularis muCOS85 and 



