372 



THE DIGESTIVE SYSTEM 



ship. The 'chromaffin cells' of the intestinal epithelium were first 

 recognized by Schmidt, who designated them as 'yellow cells' (Arch, 

 mikr. Anat., Bd. 66, 1905). Ciacco (Arch. Anat. e Embri., 6, 3, 1907) 

 reports similar cells also in the duodenal (Brunner's) glands. Champy 



(Compt. rend. Soc. Biol., T. 66, 1909)' 

 has described also mitochondria in the 

 cells of the intestinal glands. 



The intestinal glands are confined to 

 the narrow deeper zone of the intestinal 

 mucous membrane. Their lumen, after 

 fixation, contains only the coarsely reticu- 

 lar mucous secretion. 



The student should be warned to dis- 

 tinguish carefully between the transverse 

 sections of the tubular glands which are 

 confined to the deep zone of the mucous 

 membrane and the similar sections of the 

 villi which are only found in the super- 

 ficial zone and whose epithelial coat, in- 

 stead of inclosing a mere reticular mass 

 of mucous secretion invests an organized 

 body of diffuse lymphoid tissue. 



THE DUODENAL (BRUNNER'S) GLANDS. 

 The duodenal glands of Brunner are 

 tubulo-acinar glands which furnish a 

 muco-albuminous secretion. They appear 

 to represent the continuation into the in- 

 testine of the pyloric glands of the stom- 

 ach, and they occur in decreasing propor- 

 tion throughout the entire length of the 

 duodenum; around the duodenal papilla?, 

 however, they become locally more numer- 

 ous. They are sharply distinguished from the pyloric glands by their 

 larger size. Moreover, the secreting portion of the duodenal glands is 

 only found in the submucosa and the deeper part of the mucous mem- 

 brane, where the secreting acini form very numerous groups, the tu- 

 bules of each of which are connected with the terminal subdivision of a 

 duct. 



The ducts of the duodenal glands open on the free surface between 

 the villi by means of crypt-like tubules which are lined by tall columnar 



FIG. 346. RECONSTRUCTION 

 MODEL OF A BRUNNER'S 

 GLAND, FROM THE HUMAN 

 DUODENUM. 



Three partially blended ducts 

 pass into the submucosa and end 

 in expanded alveoli. X 344. 

 (After Maziarski.) 



