26 THE STRUCTURE OP THE GLANDS OF BBUNNEB 



which are indistinguishable by cytological characters from those of the glands of 

 Brunner. In the pyloric glands many cells of Stohr may be seen. In the glands of 

 Brunner I have failed to find any of these elements. 



In the American porcupine the duodenum presents at its beginning a flask- 

 shaped dilatation about 3 cm. in length, into which the common bile duct opens. The 

 glands of Brunner are not, however, confined to this, but extend, as in the rabbit, for 

 a considerable distance into the duodenum. The piece of duodenum available for this 

 examination was 12 cm. in length and throughout contained glands of Brunner. In 

 no part of this area do the glands reach any considerable development. They form a 

 relatively thin layer in the superficial portion of the submucosa, composed of rather 

 small lobules often consisting of a few tubules only. Some tubules may also be seen 

 in the tunica mucosa above the lamina muscularis mucosse. The glands begin 

 immediately distal to the pyloric sphincter. At this point a well-defined group is 

 present in the mucosa and forms the direct continuation of the pyloric glands of the 

 stomach, although they open either directly, or by means of a gland of Lieberktthn 

 between the villi. Separating these from the small lobules in the submucosa there is 

 a well-defined lamina muscularis mucosse composed of a thick outer longitudinal 

 stratum and a thin incomplete inner circular layer. In the rest of the region the 

 lamina muscularis mucosae is thin, composed almost wholly of longitudinal fibers and 

 much interrupted by the passage of ducts. The ducts of the glands of Brunner after 

 passing through the lamina muscularis mucosaa open either directly into the bottoms 

 of the glands of Lieberkuhn or ascend as independent ducts for a short distance and 

 open into the sides of the glands of Lieberkuhn shortly' before reaching the surface. 

 In the latter case the duct is usually joined by a number of tubules which are located 

 in the mucosa. There are also in the mucosa small groups of Brunner' s glands which 

 open independently into the sides or bottoms of the glands of Lieberkuhn without 

 being connected with those located in the submucosa or with their ducts. 



The glandular tubules are formed of cells of a rectangular shape 8 ^ to 17 M in 

 height, the average being about 13 /*. The cells show great uniformity in structure, 

 notwithstanding differences in size. The nucleus has a distinct oxyphile nucleolus, is 

 situated at the base of the cell, and is oval in shape, but is in some cases somewhat 

 flattened or irregular from compression. The body of the cell is transparent in hamia- 

 toxylin preparations. There is but little cytoplasm at the base of the cell, but the 

 secretion is, as in most other mammals, distinctly divided into two masses by a bridge 

 of cytoplasm similar to that illustrated for the opossum in Fig. 2. The proximal mass 

 also, as in the opossum, exhibits a coarser cytoplasmic network than the distal mass. 

 In strong muchaematein a coarse network, composed of deeply blue-stained trabeculse, 

 is seen. 



The few pyloric glands which are found on the intestinal side of the summit of the 

 pyloric sphincter are exactly similar in all structural details to the glands of Brunner. 

 On the gastric side, however, marked differences are visible which are particularly 



302 



