54 THE TROPHOBLAST AND ITS SURROUNDING BLOOD SPACES. 



by means of a drop of blood which coagulates and later becomes 

 organized. (Peters, Leopold, Graf v. Spec.) 



That it should be closed by a blood drop is not at all surpris- 

 ing, since the ovum breaking into the mucosa, so to say, has set 

 a small wound and has opened up a blood cavity. From the lat- 

 ter a small amount of blood could easily ooze. This, then, would 

 at the same time be the most natural process o*f restoration of 

 the injury produced by the process of embedding. 



Without these preliminary remarks it would be rather difficult 

 to understand the following chapter dealing with the trophoblast. 



In studying the trophoblast I had the same experience as 

 Peters. The microscopic pictures are so varied and oftentimes 

 so complex that it requires considerable time to properly interpret 

 the findings. One often wonders what bold conclusions were 

 drawn by onesself and other writers, concerning the very early 

 stages of development, from the study of ova representing a 

 much later period of pregnancy. 



It is obvious that it should be the aim of both gynecologist and 

 pathologic anatomist to search for all available material in order 

 to place our knowledge, concerning the first days of embryonic 

 life, upon a more secure basis. 



After having followed the ovule up to its entrance into that 

 irregular blood space of the mucosa, it becomes interesting to 

 understand the action and functions of the ovum for the pur- 

 pose of sustaining its existence. This is accomplished chiefly 

 by means of the trophoblast. 



IV. 



THE TROPHOBLAST AND ITS SURROUNDING BLOOD 

 SPACES. THE INTERVILLOUS CIRCULATION. 



In presenting this subject the following order seems the most 

 appropriate : With the aid of sections 50 to 100 taken from the 

 center of the ovum we elucidate : 1. THE BOUNDARIES OF 

 THE EIANLAGE AND THE TRO'PHOBLASTIC PRO- 

 CESSES. 2. THE MANNER BY WHICH THESE TROPH- 

 OBLASTIC PLUGS BECOME FASTENED TO THE IN- 

 NER WALL OF THE OVULAR CHAMBER. 3. THE 

 BLOOD SPACES LYING BETWEEN THE TROPHO- 

 BLASTIC PROCESSES. 4. THE RELATION OF THESE 



