Edward A. Boyden

Experimental Obstruction of the Mesonephric Ducts.

In a previous paper 1 the writer showed that destruction of the growing ends of the Wolffian ducts in young chick embryos resulted in the failure of these ducts to establish connection with the cloaca. Under these circumstances, the Wolffian bodies became hydronephrotic, the cloaca failed to differentiate a urodaeal sinus, the allantois remained rudimentary, and the chicks died not later than the end of the sixth day from either lack of oxygen or a possible retention of urine. Since up to that time the allantoic fluid of normal embryos had never been analyzed by modern microchemical methods, the latter possibility could not at first be determined. But investigations begun in 1924 1 have shown that the end product of nitrogen metabolism in chick embryos is uric acid; that measurable amounts of it appear in the allantoic fluid as early as the fifth day of incubation; that it is eliminated in rapidly increasing amounts up to at least the 15th day 2 ; and that during all this time, from the 5th to the 15th day) the mesonephric tubules undergo rapid increase in both length and volume. 3 The present article deals kvith the effect of experimental obstruction of the Wolffian ducts upon the nephrogenic tissue of the embryo. In this connection it should be recalled that the rudimentary pronepliros gives rise to the IYolffian ducts; that from the 20th to the 30th sonntes these ducts are joined by the definitive mesonephric tubules; antl that after the lon-er end of each duct has given rise to the nietanephric diverticulum the latter is joined by metanephric tubules derived from the nephiwgenic tissue of somites 31 to 33 (Lillie). In all cases in which the writer has prevented one or both Wolffian ducts from reaching the cloaca, the ureter on that side has never formed, and no metanephric tubules have developed.

Rate of Emptying of Biliary Tract Following Section of Vagi or of All Extrinsic Nerves.

Previous experiments have demonstrated that section of the specific nerves to the choledochoduodenal junction in the cat so retards emptying of the gall bladder that double the time is required to empty half its contents after a meal of egg-yolk. Subdiaphragmatic section of the left vagus has approximately the same effect but when the right vagus is cut the time is tripled. Section of all splanchnics produces little change. 1 The evidence suggests that severance of the right vagus removes not only the fibers which activate the gall bladder but those which release the sphincter of Oddi by inhibiting the local nerve net that maintains its tonus between meals. Surprisingly, a continuation of these experiments has shown that severance of both vagi, or complete denervation of the biliary tract (vagi and splanchnics), has no retarding effect on the rate of emptying, i.e., gall bladder and sphincter respond to hormone- producing food at least as fast as in the controls. Since it is known that section of one vagus does not affect the rate of emptying of the stomach 2 but that section of both vagi relaxes the pyloric sphincter and decreases the initial time required for passage of food into the duodenum, 3 the rate of emptying of the denervated biliary tract may be explained on the basis that loss of vagus effect on the biliary musculature is compensated for by increased hormonal action resulting from faster discharge of hormone-producing food into the duodenum. Contrary to some earlier reports on section of nerves to the intestine 4 it can be stated that severance of all extrinsic nerves to the sphincter of Oddi, although resulting in destruction of preganglionic fibers, does not cause degeneration of the ganglion cells and postganglionic fibers (Fig. 1 C).

Localized Pain Accompanying Faradic Excitation of the Stomach and Duodenum

The following observations, hitherto unreported, were made during the course of experiments designed to test the reaction of the human gall bladder to faradic stimulation of the gastro-intestinal tract. 1 Eleven medical students cooperated in this undertaking, several of them submitting to repeated experimentation. The device selected for stimulating the gut tract was a standard Rehfuss tube enclosing a copper wire soldered to the metal olive at the end of the tube. The other electrode consisted of a moist pad fastened to the arm of the subject. Through this circuit was sent an induction current that was almost intolerable when tested by the lips, but which was not unbearable when applied to the gut, causing sensations varying from barely perceptible, gnawing sensations, to heartburn and sharp colicky pain. With the aid of fluoroscope and barium meal, it was ascertained that when the olive was pushed against the wall of the stomach the current caused ring contraction of the gut and then increased peristalsis distal to that point. In each case the duration of the current was 10 seconds. Figure 1 (left) records observations made upon one student on 4 different days. The circles indicate varying positions of the electrode in the gut (as determined by X-rays); the dots the site of the pain area on the abdominal wall. With the subject prone, excitation of the mid-pyloric stomach was localized at the lower middle or left epigastric regions; of the pyloric antrum, at the lower middle or right epigastrium; of the pars superior (duod.) at the right umbilical or right supra-umbilical region; of the pars descendens at the right lower epigastric, the right umbilical, or the right scrotal region; of the pars inferior (duod.) at the mid-line just below the umbilicus.

Emptying of the Gall Bladder in Monkeys

It has been clearly shown that in certain species of mammals, such as the opossum 1 and the rabbit, 2 there is little if any emptying of the gall bladder after meals, although Walsh reports that partial evacuation in the rabbit may be induced by cholecystokinin. 3 It is of especial interest, therefore, to ascertain the rate of emptying of the gall bladder in animals nearest man. Through the courtesy of Dr. J. C. McKinley, 5 specimens of Macacus rhesus were made available for study, and the gall bladder of each visualized: first, by intravenous injection of tetraiodophenolphthalein, and afterwards, by direct introduction of lipiodol at the time of laparotomy. Two of the animals (both of them females) failed to exhibit shadows after the Graham test and failed, subsequently, to empty the lipiodol after a meal of egg yolk. In one of these there was a supracolic peritonitis. In the other, as revealed by serial sections, there was a subacute or chronic cholecystitis with marked infiltration of plasma cells and lymphocytes, but with intact epithelium. This condition is of value as indicating what degree of inflammation is sufficient to prevent concentration of the dye. In the remaining 3 animals (all males) the gall bladder was readily visualized and exhibited rapid evacuation of bile after a meal of egg yolk. The first one emptied half of its contents in the first 36 minutes (Graham method); the second one, 3/4 of its contents in 24 minutes (Graham method), and all of its lipiodol in 32 minutes; the third one evacuated most of its lipiodol in 27 minutes and disposed of the rest within the next 19 minutes. Nothing comparable to this initial rate of emptying has been found in any other species except man 4 and definitely establishes the supremacy of the primate gall bladder.

Reflex Inhibition of the Human Gall Bladder.

In a previous publication, one of the authors reported that merely drinking a glass of water resulted in a discharge of bile from the gall bladder. 1 In extending these observations to a large number of patients (10 in all) considerable variation was found, ranging from an individual with a discharge of 24 cc. of bladder bile after a glass of water (case G. B., Fig. 1) to one who reacted not by contraction but by dilation of the gall bladder (case B. B., Fig. 1). In discussing these extreme types with Dr. W. H. Petersen, the latter suggested that we might be dealing with persons who were differently oriented in regard to the autonomic nervous system. And, indeed, when these individuals were subjected to the Goetsch test, it was found that one extreme (B. B.) was markedly vagotonic, registering a decided fall of systolic blood pressure and of pulse rate after subcutaneous injection of adrenalin, and that the other (G. B.) was markedly sympaticotonic. No generalizations could be made about the intermediate cases. Up to the present writing we have not been able to secure a gall blader record ot another case showing so marked a fall in pulse rate. But Whether or not this reaction of the gall bladder proves to be characteristic of vagotonics, the present study is of value in that it has revealed a reversed type of response. In the individual in question (B. B., Fig. 1) we secured sudden dilation of the gall bladder, after giving the patient a glass of warm water, of cold water and of milk. That this is not merely a filling of the reservoir following abrupt closure of the sphincter but is due to relaxation of the gall blader musculature, is indicated by 2 observations: first, the rapidity with which the change takes place (see cholecystogranis, Fig. 2); and second, the contrast which it presents to case J. E. (Fig. 1) in which there is a slow filling of the gall bladder after each response to water, without marked relaxation of its muscular tonus—case which is probably characterized by so hypertonic a sphincter that even the contraction of the gall bladder after milk is relatively ineffective.

Evacuation of Gall Bladder in Female Patients with Pernicious Anemia

In an earlier study 1 it was observed that in male patients with pernicious anemia the rate of evacuation of the gall bladder was not significantly retarded by the disease, but that in a surprisingly large proportion of the cases studied roentgenologically, the gall bladder could not be visualized, notwithstanding the use of the intravenous method and the absence of any gall bladder history. Accordingly it seemed desirable to examine a comparable number of female patients. The present report is based upon cholecystographic studies of 48 consecutive, unselected patients with pernicious anemia (23 males and 25 females). In this group, 42% could not be visualized (35% of the males and 48% of the females). Also, a review of the 31, 311 necropsies recorded by the Department of Pathology for the 15-year period between 1926 and 1940, showed that of the 105 individuals having pernicious anemia, 32.4% had had either cholecystitis or cholelithiasis (or both) or had had the gall bladder removed. Furthermore the incidence of gall bladder disease increased progressively with age to the 8th decade—whereas Blalock 2 has shown that the greatest percentage of cases of biliary disease occurs in the fifth decade. These figures suggest that pernicious anemia increases the incidence of gall bladder disease and may have an etiological relation to it. Evacuation of the gall bladder in 12 female patients (average age, 58 years) showed marked retardation over the group of female controls 3 (average age, 65 years); for in the first 40 minutes after the standard meal, the pernicious anemia group had evacuated only 71.5% of the contents of the gall bladder as against 84% by the controls. The difference is statistically significant, being nearly 3 times the standard error.