56 THE TROPHOBLAST AND ITS SURROUNDING BLOOD SPACES. 



Plate XI; Fig. 22 tr, tr; Fig. 23 tr Plate XII & XIII) one no- 

 tices that the Eianlage, besides these finest processes, gradually 

 sends forth larger ones which tend to reach the inner surface 

 of the ovular chamber. Peters has very appropriately (pg. 91) 

 compared these trophoblastic processes to the arms of an oc- 

 topus. 



Here also nothing can as yet be seen of an extension of the 

 mesoderm into these trophoblastic buds. It seems that first of 

 all the ovum attempts to gain a firm hold and only later it pro- 

 ceeds to form true villi by the proliferation of the mesoderm. 



ad. 2. How and where do the ends of the trophoblastic pro- 

 cesses become attached to the wall of the ovular chamber? 



In order to answer this question we must study not only the 

 sections through the middle, but especially those through the 

 lateral portion of the ovum. (100 to 120.) A very notable 

 finding can be recorded. In speaking of the Eianlage it has 

 been stated that it is attached like a leech with a broad head to the 

 summit of the ovular envelope, but that here also the attachment 

 is effected by a thin layer of ectoblast containing syncytial cells. 



In looking over the sections through the lateral portion of the 

 ovum one notices that coincident with the gradual disappearance 

 of the Eianlage, broad trophoblastic processes and columns along 

 the whole periphery of the ovum but especially near its sum- 

 mit, like a network, connect the Eianlage with the chamber walls. 



The processes and columns consist of oval Langhans' cells 

 darkly stained, closely pressed together and filled with round and 

 oblong nuclei. Everywhere, especially so laterally, they are 

 covered with large syncytial cells, some of them oblong irregu- 

 larly shaped, others standing on their edge filled with oblong 

 crescent shaped or with small nuclei tightly pressed together. 



The ends of these processes with their syncytial cover have 

 penetrated deeply into the thin layer of tissue over the summit of 

 the ovum (Figs. 16 & 17 sy. Plate IX). Here, where the 

 covering fibrinous band has almost disappeared, we meet with 

 conglomerations of syncytial cells. Lying close together they 

 almost create the impression of rests of surface epithelium (Figst 

 12 & 13 sy. Plate VII) ; yet their connection with syncytial cells 

 emerging from deeper layers is so evident that any idea of their 

 relation to rests of epithelium must be repudiated. There is still 

 another fact which prohibits such an assumption. It has been 

 mentioned several times that from the surface of the mucosa a 

 narrow, irregular band resembling degenerated epithelium creeps 

 over the edge of the fibrinous cover. In these sections also, in 

 which the fibrinous cover is still missing, appearing only in later 



