28 THE STRUCTURE OP THE GLANDS OF BRUNNER 



instance in which the writer has seen in the pyloric glands of mammals large granules 

 which are unstainable by mucin stains and which might be confused with zymogen 

 granules. They do not occur in the apical zone of the cell in the midst of the mass 

 of secretion, nor may they be seen in the cells of the glands of Brunner. Similar large 

 granules occur in the mucous cells of the pyloric glands of Plethodon cnjthronoius. 



In the ground hog (Arctomys monax) the glands of Brunner are direct continua- 

 tions of the pyloric glands. They begin at the summit of the pyloric sphincter and 

 extend a considerable distance into the intestine in one specimen throughout the 

 whole piece, 9.5 cm. in length, available for examination. At no point does the 

 glandular layer reach any considerable thickness, the maximum, measured in one speci- 

 men, being 0.3 mm. At the beginning of the intestine, the lamina muscularis mucosse 

 is absent and the glands located in the tunica mucosa and in the tola submucosa 

 respectively form a continuous mass. Farther down the lamina muscularis IUUCOSJB is 

 represented by an interrupted band of longitudinal fibers which subdivides the glands 

 of Brunner into two groups, one located in the submucosa tissue, the other in the 

 mucous membrane. At the lower end of the piece the lobules are small, few and scat- 

 tered, and are entirely confined to the tela submucosa. 



A few of the ducts at the beginning of the zone reach the surface between the 

 villi. Most of them, however, and all of those of the distal portion of the zone, are 

 connected with the surface by means of a gland of Lieberkuhn. 



The glands are formed of rather large tubules, 31 /* to 61 fj. in width, of which the 

 lumen forms approximately one-third. The tubules branch much less freely than in 

 the other genera already described. 



The tubules are formed of large, transparent, secretion-filled cells 12.7 p to 19.5 ^ 

 in length. The nuclei of these cells are elliptical, in some cells crescentic, in outline, 

 and placed transversely in the proximal ends of the cells. The transparent bodies of 

 the cells exhibit a coarse meshed reticulum composed of cytoplasmic trabeculae, the 

 meshes of which are filled with the secretion. The latter forms a single continuous 

 mass in each cell, but the similarity in secretory mechanism between this cell and the 

 corresponding cells of the opossum is shown by the differences in character of the 

 cytoplasmic trabeculse of the proximal and distal portions of the cell. In the proximal 

 portion, the trabeculae are coarser, with smaller meshes, so that the cell when stained 

 by a strong cytoplasmic stain exhibits two zones. At the junction of these two zones 

 there is .a slight concentration of the cytoplasm, probably corresponding to the trans- 

 verse band which in the intermediate stage of the opossum's cells separates the two 

 masses of secretion. 



In the ground hog the cells of the pyloric glands are similar to those of the 

 glands of Brunner. The secretion of both stains readily in the stronger muchse- 

 matein and in mucicarmine. In Mann's methyl blue-eosin the secretion of the pyloric 

 glands, as well as that of the cells of the independent ducts of the glands of Bruuner, 

 stains more intensely than that of the glands of Brunner. 



304 



