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parative anatomical considerations plead for my opinion (see below). 



The uterine epithelium gradually disappears in all places where 

 the germinal vesicle is in contact with it. There is never question of 

 proliferation now. 



Relatively soon already (even with a very extensive material the 

 transitions are difficult to follow) a second stage sets in, in which 

 by proUferation of the stroma cells, beginning from the surface, a 

 dish is formed of cubical cells with granulated plasm (decidua), 

 which extends more and more, while the above described cavities 

 disappear, probably by resorption under influence of the pressure. 

 In the mean time the decidua cells at the surface undergo further 

 alterations and are resorbed (verj^ likely by the umbilical vesicle, 

 since in this and in the cells of the wall a similar substance can 

 be found), so that a fine meshy texture is formed by the peripheral 

 part of the cells remaining; by the pressure this meshy texture is 

 compressed to a thin layer of lamellar structure, which in its youngest 

 parts still shows the meshes. Vessels are not or scarcely found in 

 the decidua. The separation between the decidua and the little or 

 not changed subdecidual tissue outside it, is the limit to which the 

 differentiating processes in the wall have progressed, at the same 

 time approximately the limit, marking how far the agglutination 

 of the germinal vesicle with the wall has advanced ; it may therefore 

 be called "differentiation limit". 



At this time the above described giant cells become fewer and 

 fewer in number, have an increasingly degenerate appearance and 

 soon disappear altogether. At the mesometral side especially by 

 proliferation of the epithelium an increase in number and size of 

 crypts takes place (not of glands). 



A second period in these pre-placentary stages is characterised for 

 the ovule by the origin of the amnion etc. The growing embryo 

 seeks place in an impression of the upper part of the umbilical 

 vesicle, which becomes more and more accentuated. At the umbilical 

 vesicle begins, starting again at the part that is most distant from 

 the embryo, an outgrowth of the trophoblast cells with their nuclei, 

 which process also continually advances towards the embryonic pole. 



Characteristic for this stage are different processes beginning on 

 the ovule as well as on the uterus in equatorial bands above the 

 differentiation limit, and from here also proceeding mesometrally on 

 all sides. For the ovule these processes consist in a proliferation of 

 the trophoblast which will later cover the outer layer of the amnion 

 fold ; irregularly placed, dark, polygonal cells with distinct borders 

 appear; on the surface of the trophoblast small cell-heaps rise every- 



