ON THE FATE OF THE HUMAN EMBRYO IN TUBAL PREGNANCY. 33 



wall which also enter the clot are also dissociated; that is, they disappear by his- 

 tolysis. At another point a tuft of villi reaches to the tube wall and there the 

 trophoblast cells mingle with the tissues of the tube wall. At their tips is an exten- 

 sive vacuolated trophoblast, the lakelets of which are partly filled with fresh blood. 

 No other specimen better demonstrates that the trophoblast feeds upon a small 

 quantity of fresh blood, but that a large quantity of older blood can not be assimi- 

 lated by it. It attacks such clots as do the leucocytes. It is only when the tropho- 

 blast receives small quantities of fresh blood that we can view its relation to the 

 tube wall as normal. 



The last specimen, containing a normal fetus, whose implantation I have had 

 an opportunity to examine, is No. 484. It contains a fetus 96 mm. long. The 

 placenta is partly filled with a large hemorrhagic mass, within which many villi 

 are necrotic. Between these masses there are tufts of villi, often 20 mm. in diameter, 

 which reach to the tube wall and are intimately connected with it. At the point 

 of juncture between the trophoblast and the tube wall is a considerable amount of 

 fibrinous tissue. This the trophoblast invades or perforates and reaches to the 

 blood vessels of the muscular layer, which are tapped, so that we have long strands 

 of trophoblast reaching from the tips of the villi to the blood vessels; but here also 

 there is very little blood between the villi. Between the villi in this region are 

 numerous masses of necrotic trophoblast that have largely undergone fibrinoid 

 degeneration; otherwise we have here a picture practically identical with that 

 obtained from the uterus at like stages of development. It does not differ materially 

 from the condition shown in Grosser's figures 124 and 131, from specimens a little 

 older than No. 484. 



CONCLUSIONS REGARDING NORMAL IMPLANTATION. 



The conclusion drawn from the study of normal implantation in the tube is 

 that in the early stages most of the ova are destroyed by the hemorrhage which is 

 produced for their nourishment. If the dam built up by the trophoblast is sufficient 

 to check the flood in part, enough villi will remain to nourish the ovum. Through- 

 out development such a catastrophe is imminent, and we may have a destruction 

 of the ovum at any time. When the tube ruptures into the broad ligament, the 

 space for the chorion becomes sufficiently large for new villi to grow and attach 

 themselves. If there are enough of these, an occasional hemorrhage will not impair 

 their development. In all cases the ovum within the tube is at a decided disadvan- 

 tage because it does not have a decidua to aid in producing a normal implantation. 

 Whether this point is of much importance in the second half of pregnancy can not 

 be answered at present. I am rather of the opinion that the decidua is of the greater 

 moment at the beginning of uterine pregnancy. 



