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



without producing any hemorrhage. It appears, then, that in the earlier stages 

 there is an extensive hemorrhage, so that there is sufficient blood to fill all the spaces 

 between the villi, but later, as the ovum grows larger, the tips of the villi seem to 

 protect the intervillous spaces by throwing up a wall or dam of trophoblast, which 

 seems to hold back or plug the blood-vessels as soon as they have been eroded. The 

 process is severe and must of necessity be accompanied with hemorrhages, but if 

 these are not too extensive the effused blood can easily be devoured by the adjacent 

 trophoblast. In general, however, this process is marked at the tips of the villi, 

 but not between them. In fact, if there is a large hemorrhage, the ovum is rapidly 

 detached, as is so frequently met with in tubal pregnancy. Sometimes in normal 

 tubal pregnancies there are hemorrhagic areas measuring several millimeters in diam- 

 eter. These seem to retard the growth of the ovum. If they are small, it appears 

 as though the blood is prevented from forming a coagulum, possibly owing to some 

 inhibitory substance secreted by the trophoblast. When the hemorrhage is large 

 it appears as though this substance can not prevent coagulation, but in the neigh- 

 borhood of the villi we usually have fluid blood, judging by the morphological 

 appearances under the microscope. 



NORMAL EMBRYOS IN THE TUBE. 



Among the many small ova found in the tube very few contain normal embryos. 

 Either the embryo is deformed (as in No. 729), it is missing (as in No. 754), or the 

 entire ovum is reduced to a small clot (as in Nos. 367 and 539). In these specimens 

 the embryonic mass was either partly implanted or lying free in the tube lumen, 

 showing that in many cases the ovum becomes detached, begins to disintegrate, and 

 if not aborted into the abdominal cavity would ultimately be absorbed. In all 

 probability abortion into the abdominal cavity is a common process, for we fre- 

 quently see the ovum breaking up into pieces and scattered for long distances in 

 the tube, and in some instances we have remaining a very few fibrous villi in the 

 tube folds as the only indication of a pregnancy (plate 2, fig. 2). 



If the pregnancy takes place in the uterine end of the tube, the ovum seems 

 to find a better lodgment that is, it becomes implanted in the muscle wall and 

 frequently eats through it. This is usually the case in an early perforation, 

 for instance, in No. 729 (plate 10, fig. 3) the implantation was near the uterus, 

 possibly at the attachment of the broad ligament. This burrowing into the tube 

 wall could readily cause a perforation. If, however, attachment takes place on the 

 broad-ligament side of the tube, perforation is less likely to occur immediately, but 

 when it does occur it is into the broad ligament. This is easily understood, because 

 it is only in this direction that the chorion can find sufficient tissue for a firm 

 attachment. Such is the case in specimen No. 790, which contains an embryo 20 

 mm. long. Here there was such an extensive mixing up of the tissue that the 

 specimen was at first believed to be one of ovarian pregnancy; more careful study, 

 however, showed that it was a tubal pregnancy which had ruptured into the broad 

 ligament. 



