THE STOMACH AND INTESTINE. 



28; 



sympathetic ganglia. The dendrites, the number of which varies 

 for the different cells, divide and redivide in the ganglia, some ex- 

 tending into the nerve bundles uniting the ganglia. The neuraxes 

 of the sympathetic neurones of the ganglia form nonmedullated 

 nerve-fibers, which leave the ganglia by one of the several roots 

 possessed by each ganglion, and, after repeated division and forming 

 intricate plexuses in the circular and longitudinal layers of the mus- 

 cular coat, terminate on the involuntary muscle-cells of these layers. 



The plexus in the submucosa, known as the plexus of ' Meissner, 

 is similarly constructed, although it contains fewer and much smaller 

 ganglia and the meshes of the plexus are much finer. It commu- 

 nicates by numerous anastomoses with the plexus of Auerbach. 

 The neuraxes of the sympathetic neurones of this plexus have not 

 been traced, with any degree of certainty, to their terminations. 

 Numerous nonmedullated nerves enter the muscularis mucosae and, 

 according to Berkley (93, I), form in the dog terminal bulbs and 

 nodules which perhaps rep- 

 resent the endings of motor 

 (sympathetic) nerves in this 

 layer. Nerve-fibers have also 

 been traced into the mucosa, 

 and in the vicinity of the 

 glands and in the villi are 

 found numerous exceedingly 

 fine nerve-fibers which inter- 

 lace, but in the greater por- 

 "tion of the intestinal tract the 

 endings of these fibers have 

 not been fully worked out. 

 That they end on the gland- 

 cells seems very probable 

 from observations made by 

 Kytmanow (96), who was 



able, by means of the methylene-blue method, to stain plexuses 

 of fine nerve-fibrils surrounding the gastric glands of the cat, some 

 of these fibrils being traced through the basement membrane of 

 the glands and to and between the gland-cells, where they ter- 

 minated in clusters of small nodules on both the chief and parietal 

 cells. The plexus of Meissner is not so well developed in the 

 esophagus as in the remaining portions of the digestive tract. 



That the cell-bodies of many of the sympathetic neurones of 

 Auerbach's and Meissner's plexuses are capable of being stimulated 

 by cerebrospinal nerves seems certain from observations made by 

 Dogiel (95), who has shown that many small medullated nerve- 

 fibers which enter the digestive tract through the mesentery (small 

 and large intestines) terminate after repeated division in terminal 

 end-baskets which surround the cell-bodies of many of the sympa- 

 thetic neurones of these plexuses. Similar nerve-fibers ending in 



Fig. 226. From thin section of esophagus 

 of cat, showing the epithelium and a portion 

 of the mucosa and the terminal nerve-fibrils in 

 the epithelium (from preparation of Dr. DeWitt). 



