109 



Zellen erfolgt, welche letztere später zu Grunde gehen (Tupaja, Maul- 

 wurf; vielleicht auch Fledermaus und Schwein), oder endlich, es wird 

 die trophoblastische Deckschicht oberhalb der Keimscheibe sehr erheblich 

 abgeflacht, wodurch der formative Epiblast und der Trophoblast dem 

 Anschein nach in engstem genetischem Verbände stehen, während in 

 "Wirklichkeit der Verband zwischen dem peripheren Bezirk des Tropho- 

 blastes und seinem als Deckzellenschicht zu bezeichnenden Abschnitt 

 auch hier die primäre, die anfänglich kontinuierliche Verbindungsweise 

 gewesen ist (Lepus, Sorex)." "Der Entwickelungsgang kann eine Ab- 

 kürzung erfahren, indem die Amnionhöhle innerhalb eines vom Tropho- 

 blast verfrüht abgetrennten Epiblastzellenhaufens spontan erscheint 

 (Cavia, Pteropus)." 



I hope that these quotations may dispel eventual doubts about the 

 significance of the term trophoblast. 



I have now to consider the application of that term in gynaecology, 

 more especially its application to the placentation of man and of other 

 mammals. I find that its use has become more general with English and 

 American than with German authors and at the same time it would seem 

 as if al^ in this case a tendency to misunderstand the real significance 

 of the term has sprung up. 



This tendency is very naturally explained when whe consider how 

 important a factor for the process of placentation, the proliferation of 

 trophoblast-cells, has been shown to be. This proliferation is especially 

 verjr luxurious in man (Siegenbeek van Heukelom, Peters), in the 

 hedgehog (Hubrecht), whereas in many other Insectivora and Rodents 

 its multiform complications are exceedingly varied. In consequence 

 many investigators have been led to believe that the name trophoblast 

 was originally restricted to those proliferating regions, whereas we have 

 demonstrated above that this has never been so. Add to this that the 

 proliferation of cells contributing to the formation of the placenta yet 

 in another wa}^ is apt to lead to confusion because such proliferation 

 is in no way limited to embryonic cells but is also noticed — some- 

 times to a most considerable extent — in maternal cells belonging to 

 the epithelial lining of the uterus or to the subepithelial maternal tis- 

 sues. In this way debates have arisen between Strahl and Lüsebrink 

 on one side, Duval, Van Beneden and myself on the other of which 

 debates the object was to make out in how far the material of the pro- 

 liferating placenta should be looked upon as maternal, in how far as 

 embrj'onic (trophoblastic) tissue. 



These debates will no doubt in the course of time, as the number 

 of carefully observed cases increases, lead to a unanimous interpretation. 

 As it was I have myself, for sheer diffidence of attributing too pro- 

 minent a part to trophoblastic proliferation (of which I was nevertheless, 

 together with Duval, the first advocate) in one case stopped short of the 

 real solution and have for the hedgehog restricted the extent of the 

 trophoblast more than was necessary. Since then I have corrected this 

 in a doctor-dissertation of one of my pupils (Resink, 1903) but there 

 is no doubt that I am myself thus responsible for a certain amount of 

 vagueness and misrepresentation which has prevailed in the application 



