Lebecljew seeks to answer the following two propositions: leL Does there exist, in the limiting chorional layer of children at term, in cases .of dropsy of the amnion, the capillary net-work described by Jungbluth ? 2d. What circumstances determine this persistence of vascular permea bility which is absent under normal conditions? Lebedjew has proved microscopically the existence of this plexus in a case of hydramnion with a dead child; but there existed aortic stenosis, hypertrophy of the right ventricle, and consequently stasis in the inferior vena cava. This obstruction to the flow would be transmitted to the placenta through the portal and umbilical veins. This probably interfered with the obliteration of the plexus in question, and determined the in creased transudation. Lebedjew claims that dropsy of the amnion is due primarily to a fcetal anomaly, and hence arises the large mortality in these cases Sallinger holds that the amniotic fluid is derived exclusively from the fcetal circulation; coming at the commencement of pregnancy from the fcetal skin, later from the cord and the vessels of the fcetal placenta, and only towards the end, in greater or smaller quantity, from the kidneys. Only a small amount of fluid is derived, during the early months of preg nancy, from the skin, which soon becomes covered with epidermis, and secretes less freely; the greater part of it is due to the resistance that the foetal circulation encounters in the placenta, and in the cord. Excess of resistance will cause dropsy of the amnion; and clinical observation shows that obstruction of the veins that bring blood to the fcetus, either in the placenta or the cord, or at the umbilical ring or in the liver, is the cause of the affection.
Sallinger thus holds that hydramnion is due to mechanical disturb— ances of the fictal circulation, or to variations in the entire mass of the fcetal blood, and not, as Jungbluth says, to special anatomical conditions of the placenta. He performed a series of experiments, which tended to prove that the liquor amnii, whether in normal or abnormal quantity, is a direct product of transudation from the umbilical vein and from its ramifications in the placenta. Taking healthy and untorn placentm, and introducing a canula into the umbilical vein, he injected under a con stant pressure pure water and defibrillated bullock's blood. The injected liquids transuded through the amnion with great rapidity; thus: 1st. With a pressure of 36 inches upon the single vein of a small cord, there passed in one hour 25.43 grains.
2d. With the same pressure and a thick cord, 28.91 grains.
He once employed the double placenta of twins, and obtained: 3d. With a pressure of 36 inches on both veins together, 56.31 grains. 4th. With a pressure of 74 inches on the vein of the thick cord, and of 36 inches on the vein of the thin one, in half an hour, 60.94 grains.
5th. With a pressure of 50 inches upon the thin cord, and of 36 inches upon the thick one, in half an hour 75.61 grains.
6th. With an equal pressure of 50 inches on both, in the same time, 50.68 grains.
Bar has repeated these experiments of Sallinger, and concludes with him: 1st. Under a certain pressure the fluids contained in the umbilical
vein may transude into the amniotic cavity.
2d. Under an equal pressure fluids will not transude through the walls of the umbilical arteries.
These two theories each have their partisans and their adversaries. Thus, Winckler has never been able to prove the existence of Jungbluth's capillary plexus, but believes that there is a lymphatic plexus in the cel lular layer of the chorion, which opens freely into the cavity of the egg through the amniotic epithelium, exactly as occurs in the diaphragm. These canaliculi are the source of the fluid in dropsy of the amnion. A considerable dilatation of these lymphatic vessels has been found by Winckler in a case of hydramnion complie,ated with fcetal rachitis.
Levison and Gusserow support Jungbluth's theory. The former, by means of injections into the vessels of the umbilical cord, found the capil laries well developed in the membranous lamina of the placenta of pre maturely born infants, while in those born at term, there was none; but in cases of hydramnion, either at term or before it, he found it very abundantly developed.
He admits the presence of the lymphatic vessels which, with Winckler, play the part of the vasa propria of Jungbluth. May not, he asks, dis t urbances of pressure in the fcetal circulation prolong the permeability of the vasa propria of the placenta, and thus increase the amount of liquid that passes through them.
Weil and Waldeyer also admit the existence of Jungbluth's vasa pro pria. Bar contests their existence, claiming that Jungbluth never de scribed them as being in the amnion, but only as being in contact with its lower surface, being situated below it. He denies the correctness of the designation vasa propria, especially as in the amnions of some of the lower animals there exist true proper vessels. The branches of the um bilical vein that ramify over the foetal surface of the placenta, give off a capillary plexus that ramifies and anastomoses with itself, and then pene trates the placental tissue. Injected with a colored fluid, the plexus be comes visible to the naked eye.
We, ourselves, have found a venous net-work applied to the deep face of the placenta; but never a capillary one. Nor have we ever been able to inject it with prussian blne. Nevertheless, we do not absolutely deny its existence. We have, ourselves, seen in cases of dropsy of the amnion a considerable turgescence of the branches of the umbilie,a1 vein; we have even in one case seen the chorionic vessels more largely open than in the normal state; but Jungbluth's description certainly does not apply to all cases of dropsy of the amnion, and permeability of the vasa propria, to the end of pregnancy, cannot be the sole cause of the affection. For: 1st. If the vessels are obliterated at the middle of pregnancy, how can the quantity of the liquor amnii increase continuously until the time of preg nancy ? 2d. We have been unable to demonstrate the capillary plexus in some cases of dropsy of the amnion.