40 THE STRUCTURE OP THE GLANDS OF BRUNNER 



contain distinct intracellular ducts, and exhibit the three characteristic zones of 

 structures described by Zimmermann (1898) for the parietal cells of the stomach. As 

 in the latter the nuclei may be multiple. 



The cells of the pyloric glands in man resemble very closely in size and structure 

 those of the glands of Brunner. In general, in the former the subdivision of the 

 secretion into two masses is more obvious and the proximal mass contains coarser 

 cytoplasmic trabeculae. 



The cells of the glands of Brunner of the old subject were, as has already been 

 remarked, considerably atrophied. They measured 12 /* to 14 n in height. The 

 lumen showed a corresponding enlargement. In most of the tubules the secretion 

 stainable in strong muchsematein was confined to a narrow zone less than 2 n in width 

 along the lumen. The rest of the cell was occupied by a continuous mass of cytoplasm 

 containing the oval nucleus. In some of the cells, however, a second small proximal 

 mass of secretion occurred in the midst of this cytoplasm between the nucleus and the 

 narrow distal mass, and in a few tubules the two had become confluent, forming a 

 single large mass of secretion, filling all of the space between the now flattened nucleus 

 and the lumen. 



VIII. DISCUSSION OF RESULTS 



The results of this investigation show that there is a remarkable uniformity in 

 the nature and structure of the glands of Brunner of many mammals. In eighteen out 

 of the nineteen genera examined the glands are of the pure mucous type. This con- 

 clusion is based on the structure of the cells of the glands, and on their staining and 

 microchemical properties. The evidence, which is partly negative, partly positive, 

 may be briefly summed up as follows: 



The cells of the glands, when examined fresh in serum or normal salt solution, do 

 not show easily visible secretion-granules. The granules (droplets?) of secretion like 

 those of known mucous glands correspond so closely in refractive power with the 

 mounting media that they are almost invisible. 



The cells when fixed and stained do not contain basal filaments (prozymogen), 

 and the microchemical test for organic iron indicates the presence of only a relatively 

 small amount of cytoplasmic nucleoproteid. Serous cells from other sources, on the 

 other hand, show the presence of a large amount of cytoplasmic nucleoproteid, either 

 in the form of the so-called basal filaments (composed largely of the nucleoproteid 

 prozymogen) or in the form of prozymogen diffused in the basal cytoplasm. 



The granules of zymogen in the pancreatic and gastric ferment-secreting cells 

 stain strongly in iron haematoxylin. The secretion of the cells of the glands of Brun- 

 ner remain colorless in this stain. 



A more positive and selective stain for the granules of zymogen of the stomach 

 and pancreas, Reinke's neutral gentian, as modified by the writer (1900), also gives 

 negative results with the cells of the glands of Brunner. 



316 



