20 THE STRUCTURE OF THE GLANDS OP BRUNNER 



to those of the cat. They have, as a rule, a rather large lumen surrounded by secret- 

 ing cells. The average size of the tubules is about 40 /*, but some are as much as 77 /* 

 in width. 



The cells vary in width from 11 /t to 15 p, the two extremes being often found on 

 opposite sides of the same tubule. The cells correspond very closely in structure to 

 those of the opossum ; indeed, Fig. 2 would illustrate equally well a typical tubule 

 from the mink. In each cell two well-defined secretion masses may be discerned 

 separated by a transverse band of cytoplasm. The secretion in these cells stains 

 strongly in muchcematein applied as indicated above. The amount of secretion 

 contained in the cells, and so the amount of cytoplasm, vary respectively, in the 

 material examined, with the distance from the sphincter pylori. In the glands 

 near the sphincter, the cells contain a large amount of basal cytoplasm and a 

 spherical nucleus. The proximal mass of secretion is small and stains less intensely 

 in muchsematein. Going down the zone, the size of the proximal mass progressively 

 increases and encroaches on the basal cytoplasm, the nucleus at the same time becom- 

 ing correspondingly compressed and crescentic and crowded to the extreme base of 

 the cell. 



If we compare the cells of the glands of Brunner of the proximal part of the zone 

 with the cells of the pyloric glands which immediately overlie them, there appears to 

 be an almost perfect similarity of structure. But if we compare Brunner's gland cells 

 from the duodenal end of the zone with pyloric glands several millimeters above the 

 pyloric sphincter, some differences of structure are apparent. In the latter instance 

 the tubules and cells are of about the same size, but in the pyloric glands the cells are 

 to a large extent filled with cytoplasm. The proximal mass of secretion in these 

 upper pyloric-gland cells is scarcely visible, and the distal mass next to the lumen 

 occupies often less than one-fifth of the whole length of the cell. The nuclei are 

 spherical. Again in the pyloric glands as the sphincter is approached the amount of 

 secretion in the gland cells is gradually increased. There is thus in the mink the most 

 perfect transition between the pyloric glands, on the one hand, and the intestinal 

 elements, on the other. 



IV. THE GLANDS OF BRUNNER OP ERINACEUS 



In the European hedgehog the glands of Brunner form a mass of rather large 

 lobules, beginning at the pyloric sphincter and extending a distance of 9.3mm. into the 

 duodenum. The greatest thickness of the mass is exhibited at the beginning, where 

 the lobules fill the space formed by the sudden falling off of the pyloric sphincter. 

 Here it reaches a thickness of 1.8 mm. From this point it gradually diminishes in 

 thickness to the end of the zone. 



The glands are separated from the tunica mucosa by a lamina muscularis mucosaa 

 composed of longitudinal fibers, which form a continuous layer except for a short dis- 

 tance just at the beginning of the duodenum, where the fibers are somewhat inter- 



296 



