The histological image of the pars pylorica and the duodenum of hedgehog shows little difference in substance from that of man, but locally there are found some characteristic structures. For example, the arrangement of the pyloric glands is much denser than in man, giving the appearance of compact conglomeration. The submucosa consists of a very thin connective tissue. The epithelium of the surface layer of the duodenum is of columnar type, but the deeper layers are often composed of cuboid cells, and in general, the cuticular border is lacking. No goblet cells are found here, either. The submucosa is filled with the enormously developed duodenal glands, which are distributed in two thirds of the total thickness of the duodenal wall.<br>The incoming vegetative nerve fibres supplying the pars pylorica and the duodenum of hedgehog come into close connection with the AUERBACH's and the MEISSNER's plexus, and in company with the long processes from the nerve cells in these plexus, diffuse widely in all the layers. Their termination always form STÖHR's terminalreticulum, which stands in tactile control over all kinds of cells.<br>The nerve cells in the AUERBACH's plexus are multipolar and accordingly sympathetic in nature. But the development of their short processes is very poor, so that the distinction into DOGIEL's types 1 and 2 is quite impossible. There are some primitive-looking nerve cells that have only rudimentary short processes and no long process at all. The MEISSNER's plexus in the pyloric part contains a small quantily of nerve cells, which are all of primitive infantile type. In the MEISSNER's plexus in the duodenum, no nerve cell was found at all.<br>Medullated sensory fibers are also found penetrating into the pyloric part of hedgehog, with their terminations in the submucosa, the museularis mucosae and the propria. The quantity of these fibres is larger than in man (SATO, 1949) and white mouse (OHI, 1954). The terminal formation may be classified into the four types of unbranched, simple branched, serpentine and glomerular endings.<br>Unbranched terminations are chiefly found in the muscularis mucosae and the propria, are characteristic in their often peculiar spiral courses and have terminal parts ending in sharp points. The simple branched type of terminations is formed in most cases in the muscularis mucosae and the propria and also often show spiral running courses. By the terminations of both the above types nerve fibres running into the propria ascend through the connective tissue filling the interstices of the pyloric glands and in many cases go up close to the epithelium facing the gastric foveolae, but in no case are they seen running into the gland cells. The serpentine terminations are mainly found in the submucosa, but often enogh, they are found also in the muscularis mucosae and the propria.<br>In a termination of this type, a sensory fibre of almost uniform thickness runs a characteristic serpentine course and always ends in a sharp point. In rare cases, one or two collaterals are sent out by such a fibre. The gromerular teminations are of uncapsulated extremely simple structure and are found in a small quantity in the submucosa and the propria. In the duodenum of hedgehog we find medullated sensory nerve fibres probably originating in the splanchnic nerves running through the muscular layer into the submucosa and the muscularis mucosae and even into the propria of the mucous membrane, in a number far larger than those in pars pylorica. Their terminations comprise unbranched, branched and serpentine types. The terminal ends of these terminations may in cases reach the close vicinity of the epithelium lining the duodenal glands, the intestinal crypts and the villious parts, but in no case into the epithelium itself.<br>The unbranched terminations in this part are formed in the muscularis mucosae and the propria and their terminal formation is similar to those in the pyloric part.