26 ON THE FATE OF THE HUMAN EMBRYO IN TUBAL PREGNANCY. 



strands of trophoblast remain intermingled with leucocytes and fibrin. The meso- 

 derm of the villi forming the tuft appears to be normal and contains within it blood 

 vessels filled with blood from the embryo. The tips of the tuft of villi are filled with 

 great masses of active trophoblast, which often radiate in strands to the tube wall 

 and invade it. These are accompanied in places with fibrinous strands, which are 

 more or less filled with leucocytes. Many of the villi are encircled with lakelets of 

 blood which contain no fibrin, indicating that it is not coagulated. It seems as 

 though the trophoblast secretes some substance to prevent coagulation. At points 

 the cells of the trophoblast and of the tube wall are so intermingled that it is prac- 

 tically impossible to make a separation; the trophoblast cells, however, surround 

 the small lakelets of blood, producing an appearance of cavernous tissue. This is 

 especially well marked at the tips of the villi. It appears as though the tropho- 

 blast has tapped all the veins of the tube wall, and because there is no formation 

 of a decidua it is impossible for the wall which is thrown up to prevent excessive 

 hemorrhage. We have here a true intervillous circulation which, if not arrested, 

 is bound to destroy the ovum. In this specimen, as in all the rest, there is no 

 decidua. In fact, to describe a decidua in them would be a stretch of the imagination. 

 Within the tube wall there are numerous leucocytes, just as we have in a normal 

 implantation. 



We can here describe several varieties of trophoblast : 



(1) The ordinary kind composed of quite uniform cells stacked upon the tips 

 of the villi. 



(2) The longer streams of trophoblast which radiate from the villi throughout 

 the clot and along the fibrin bands which are also present. 



(3) Trophoblast cells scattered either within the muscle wall of the tube or 

 through the clot or upon the surface of the clots. These are no doubt the cells 

 pictured by Bryce and Teacher in their Plate VI. However, these writers are of the 

 opinion that these are decidual or maternal cells, but they occur with much regularity 

 at the tips of the villi where they come in contact with the clots. They spread 

 first from the villi as solid strands and, as they spread, the cells become separated, 

 but do not come in contact with maternal tissue. They are like the pickets in 

 advance of an army. First they appear in every respect like trophoblast cells, and, 

 as they are always connected with them, I think the statement is warranted that 

 they belong to the trophoblast and are in no respect decidual. The fact is that 

 decidua can not be demonstrated in tubal pregnancy, unless indeed we describe the 

 trophoblast as such. This point, however, can not be determined when the tropho- 

 blast cells have invaded the maternal tissue. 



(4) The syncytium seems to be present where there is great activity. 



(5) A peculiar kind of syncytium which forms a network, or, to describe it better, 

 is vacuolated. There are all stages of gradation between the solid and vacuolated 

 varieties. The large masses of solid trophoblast usually appear to be located upon 

 the villi. These run out into the processes which radiate in all directions, encircling 

 other fresh blood cells. At about this stage of development numerous clear 

 vacuoles are seen in the solid mass of syncytium. These become larger and larger, 



