THE TROPHOBLAST AND ITS SURROUNDING BLOOD SPAOES. 63 



belief the blood lacunae in the trophoblast are new formed cap- 

 illaries of the decidua, whose walls either the endothelium or 

 the surrounding connective tissue had transformed into syncy- 

 tium. In none of my sections could I find any support of this 

 view. 



Like Peters, I found that the partitioned lacunae at the bor- 

 der, for the very reason that they are lying between the tropho- 

 blast columns and in fact are formed by them, are lined with a 

 layer of syncytium which ceases where the ends of the tropho- 

 blastic processes peripherally reach either the framework of the 

 mucosa or the walls of the open blood vessels. It seems ques- 

 tionable to me whether these lacunae, although of maternal or- 

 igin, can be called new formed capillaries of the decidua. This is, 

 however, a point of minor consequence. Of much more import- 

 ance is the fact, that the syncytial coat of these lacunae, as has 

 been demonstrated above, derives its existence from the Eianlage, 

 i. e., from the ectoblast. 



Most noteworthy findings have been made by Rossi Doria, who 

 examined an ovum dating from the beginning of the second week 

 of pregnancy. Aside from many observations which are fully 

 in accord with those made by Peters and myself, his findings con- 

 cerning the trophoblastic capsule are especially interesting. 



He also claims that the fertilized ovum penetrates the ex- 

 tremely congested mucosa of the premenstrual stage and enters 

 a space filled with extravasated blood. "The chorionic tropho- 

 blast excrescences from the ectoderm proliferate through the 

 blood until they reach the surrounding connective tissue. They 

 spread out with it and cause certain changes." These consist in a 

 dilation and rupture of capillaries and in the formation of new 

 extravasates in which the trophoblast forms new and longer pro- 

 cesses. A formation of new blood vessels which has been claimed 

 by Pfannenstiel has not been observed by Rossi Doria. 



According to Rossi Doria, "the trophoblast corrodes the ves- 

 sel walls and penetrates them with the syncytium. In defense the 

 maternal tissue protects itself against the invasion of the tropho- 

 blast by means of a barrier of decidual cells (Umlagerungszone). 

 In this manner both the fetal trophoblastic and the maternal cap- 

 sules are formed." 



This quotation alone proves sufficiently the great similarity be- 

 tween. Rossi Doria's and my descriptions, yet it may not be amiss 

 to also point out the harmony of our views concerning the forma- 

 tion and lining of the trophoblastic lacunae. I will cite verbatim 

 his description (pg. 503) since my observations are identical. 

 "The syncytium breaks into the decidual coat especially into 



