In the digestive tract of the human embryo, it was confirmed previously that circular muscle first became demonstrable under light microscope which was then followed by the development of longitudinal muscle with intramural plexus between 6th and 9th week of the fetal life. The present work deals with the electron microscopic findings of the digestive tract in 10 human embryos. There was evidence to show that nerve cells, presumably those of the Auerbach's plexus and their axon structure, were demonstrated in embryos of 12mm in length (6th fetal week) in the absence of discernible muscular structure. This finding is of considerable interest in the functional anatomy of the Auerbach's plexus. It was shown in microscopic cinematography that peristalsis of the fetal digestive tract initiated with the development of circular muscle. Conduction of peristalsis, however, was not directional. A divergent propagation of two peristaltic rings from a single contraction ring was demonstrated in the small intestine. One of the characteristic findings of the fetal alimentary tract was that contraction could occur anywhere along the digestive tract and peristalsis might pass in either direction. At this time of embryological development, nerve elements, particularly intramural nerves, were present in the intestinal wall of the fetus. Action potentials recorded from a cat's “nerve-free” ring muscle tube showed that contractions could propagate in either isoor anti-peristaltic direction. The mode of contraction was considered to be quite similar to that of the fetal digestive tract. Practically identical result was obtained with a “nerve-free” ring muscle tube treated with tetrodotoxin. With preparations of circular and longitudinal muscle layers devoid of mucosa and submucosal structure, iso-peristaltic conduction was more dominant. Anti-peristalsis was found to disappear approximately after the 30th week of the fetal life. It is reasonable, therefore, to suppose that the Auerbach's plexus demonstrated in an early fetal stage was not actively participating in the regulation of the peristaltic direction.

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1) Pyrodifenium bromide, 3μg-5 mg/kg, inhibited the motilities of both the stomach and small intestine of dogs, and the drug, when administered in an amount 3 mg/kg, abolished the excitatory effect of vagal stimulation upon the intestinal motility.
The drug, in the concentration of 10^-9-5×10^-5 g/ml, depressed the motility of the isolated small intestine of rabbits, guinea pigs and rats, and it in the concentration of 5×10^-5 g/ml prevented 10^-8-10^-5 g/ml of acetylholince from acting excitatorily upon the intestinal motility, while it had no influence upon the inhibitory effect produced by applying 10^-7 g/ml of adrenaline or by the stimulation of the mesenteric nerves.
2) After administering the drug, 5-10mg/kg intravenously, the inhibitory effect of the preganglionic splanchnic stimulation was reduced or completely abolished, while its postganglionic stimulation produced the inhibitory effect similar to that observed before administration of the drug.
3) It may, firstly, be concluded that the drug in small to moderate doses prevents acetylcholine released from the intramural nervous elements to act upon the intestinal motility, while the drug has no influence upon the inhibitory effect of the sympathetic nerve and, secondly, that the drug, when given in a large dose, can block the synaptic transmission at the autonomic ganglia.

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The terminal portion of the bile duct of the guinea pig was surrounded by the circular muscle fibers which were ramified from the same layer of the duodenum. The orifice of the common bile duct was opened by the rewinding action of the muscle contraction and a small amount of bile which was in the terminal portion of the bile duct was expelled.
The intraluminal pressure of the distal end of the common bile duct had an important role on the bile expulsion. When the intraluminal pressure of the ampulla overcame the resistance of the sphincter which was formed by the circular muscle, some bile in the ampulla was forced to expel into the duodenum, but a large amount of bile was pushed back into the common bile duct. The pace-maker area exsisted in the common bile duct near the ampulla.
The excitation waves travelled down to the ampulla at the speed of 30-50 mm/sec.
It seemed likely that the so-called Oddi's sphincter did not exsist independently with the duodenal muscle, but some sphincter mechanism might exsist.

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An electromyographic study of the influence of extensive resection of the small intestine on the movement of the large bowels was carried out. Thirt mongrel dogs weighing 4 to 8 kg were used for experiments.
After one-third resection of the upper, middle or lower small intestine, electrical activity of the ascending colon was markedly repressed, while that of the descending colon was not so influenced.
The action potentials of the ascending colon almost disappeared after two-thirds resection of the upper, middle or lower small intestine, but the descending colon was not influenced by these procedures.
From the results mentioned above, it is considered that the function of the remaining small intestine after extensive resection was partially compensated by the ascending colon.

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The following results were obtained through the macro- and microscopic observation of the muscular layers of human and canine intestines, which were prepared with 20% of HNO₃.
1. Both inner circular and outer longitudinal layers of the intestine are formed by the main fasciculus (named by the author) which consists of 3-7 fasciculi. The main fasciculus of the inner circular layer is spiral in shape.
2. In human, most of the main fasicucli of the inner circular layer run clock-wise spiral course, but in dogs, most of the main fasciculi of the inner circular layer run counter-clock-wise spiral course. Between the main fasciculi, there are many branches forming a fine net-work.
3. The main fasciculi of the longitudinal layer of the intestine are parallel running longitudinally. The main fasciculi are connected with many branches. No difference in human and dog is noted.
4. Dog's ileocecal valve is formed by fasciculi of the inner circular and outer longitudinal layers of the small intestine and the inner circular layer of the large intestine. The principal layer is the inner circular layer of the small intestine.

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The effect of locally injected lidocaine on the motor function of the canine stomach was studied.
1) When lidocaine was injected into the muscularis mucosae of the stomach encircling the organ, the peristalsis did not propagate across the injected site. In the portion proximal to the injected site, hypermotility was noted electromyographically consisting of prolonged discharge interval, higher amplitude, occurrence of anti-peristalsis and increase in contraction pressure of the pyloric ring. The hypermotility was seen macroscopically, also.
2) The same results were obtained after injection of lidocaine to anterior or posterior half of the circle of the stomach.
3) Following the injection of lidocaine completely encircling the stomach at two levels of about midportion of the corpus (1/2 level of the stomach) and at the borderline between the corpus and antrum (lower 1/3 level), prolongation of the discharge interval was more marked in the latter instance.

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Esophageal achalasia-like phenomena have been produced experimentally on 18 dogs after the administration of the anticholinesterase agent, phthalim-idomethyl O, O-dimethylphosphorodithioate (PMP). The agent was administered intramuscularly three times a week for 40 weeks. The dose to each group was varied from 0.5, 10, 20, 25, and as much as 50mg per kg of body weight. In the group with the dose of 20mg per kg of body weight, the symptom of vomiting or dysphagia appeared most markedly. Some dogs showed diarrhea, bloody stool and hoarseness. Upon x-ray examination, dogs showed the failure of passage at the esophago-cardiac junction and the dilatation of the lower esophagus. Intraluminal pressure recording showed the abnormal simultaneous rises of the swallowing pressure wave. Histological examination around the Auerbach's plexus showed pycnotic nuclei, swelling of ganglion cells, fibrosis and round cell infiltration. The MAO stain showed no changes. The acethylcholine-esterase stain suggested the suppression of the enzyme activity.

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Electromyographic studies on the effect of Pyrodifenium bromide (Padrin) on the motor function of the gastrointestinal tract of the dogs and human beings were carried out.
1) Electromyographically, padrin when administered intravenously in an amount of 0.5mg. per kg. of body weight had a suppressing effect on the motility of the stomach of dogs. The drug also had a marked suppressing effect on the motility of the small intestine with the amount of 0.25mg. per kg. of body weight.
2) The effect lasted from 30 to 45 min. in the small intestine and less than that in the stomach.
3) Anti-peristalsis of the stomach was restored to normo-peristalsis by Padrin.
4) The drug was effective in reducing the pain and other symptoms in 23 cases including patients of gastrointestinal disorders pre- and postoperatively.
5) Two of the 23 cases developed dryness of the mouth that was only minor side effect noted.
6) From the above-mentioned results, this drug proved to be useful clinically with its suppressing effect on the motor function of the gastrointestinal tract.

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