CYSTS OF TILE PLACENTA.
According to Millet, who has seen two cases, the walls of placental cysts are formed of layers of tissue very like that which we find interposed be tween the chorion and the amnion. The fluid they contain resembles. both in consistence and in composition, the gelatine of Wharton. The cyst is, in fact, developed in meshes of the cellular tissue, just as are those cysts of the cord which Ruysch has described under the name of hyda tidiform degeneration of the umbilical cord.
Bustamente describes a kind of cyst which is sometimes found upon the fcetal surface of the placenta, of a regularly rounded or elongated shape, and varying in size from 1 of an inch to 2 or 21 inches. They are placed below the amnion and chorion, which form their superficial or fcetal boun dary, being limited below by the placental tissue itself.
The contents of these cysts are solid and liquid. The fluid is usually lemon-colored, lactescent, and contains blood globules. Nitrate of silver causes a curdy precipitate; heat and nitric acid show the presence of al bumin. Underneath this liquid portion of the contents is a whitish or slightly yellow substance, from of an inch to 1 of an inch in thickness. Under the microscope, this tissue is seen to consist of reticulated fibrin, perhaps containing in its meshes some placental villi. Close inspection reveals the fact that it is disposed in layers. The greasy masseb of which it is apparently composed, are usually found towards the centre of the placenta, in the intervals between tho large vessels. Filially, it is not unusual to find plates on the surface in which we find a small quantity of fiuid, having the same characters as the liquid of the cysts.
How are these cysts formed ? A coagulation has taken place against the chorion, forming the plate which is the deeper layer of the cyst. The fluid may be produced in one of aeveral ways: lst. A certain quantity of blood may have been included between the coagulum and the chorion; or the blood may have appeared later, after the formation of the first layers of the plaque, from rupture of the layers. 2d. Or a little bleeding
point may be left open, and the blood then tears a cavity between the chorion and the plaque of coagulated fibrin. lire cannot attribute these to the rupture of a vessel, since in the cases examined there was no such thing. The fibrinous parietal layer also shows evidence of having come from the maternal blood of the placenta.
Ercolani has seen two cases of placental cyst. In one the entire fcetal Emrface of the placenta was sown with round tumors. covered by the cho rion, the largest being about the size of a cherry. Some had been opened, and the chorional wall torn, showing a solid material filling the depths of the cyst. They were in fact like the variety described by Bustamente. Others again were more solid, and were filled with coagulated fibrin, in which rounded masses of granular hEematin could be seen.
In the second case three hemorrhagic centres could be easily distin guished upon the fcetal surface; they were round, red in color, and about the size of small peas. Others were less prominent and more irregular in shape. In those that were cyst-like, Ercolani proved that the interior wall was formed by the chorion, which covered the whole bloody mass, of which half projected above the placental surface, while half dipped into the placental tissue, and lay in immediate contact with the effused blood. The term cyst is therefore inexact. At the placental depths of these tumors, the villosities, more fibrous than usual, formed a compact layer, certain spots in which turned out to be cella of the serotina, some of which plainly showed fatty degeneration of the nuclei. Small irregular calcareous concretiona were scattered through the masa