494 GENCHO FUJIMURA 



selected and drawn those deemed the most representative of all 

 the structural images of the afore-mentioned tissue-cells which 

 have been widely and thoroughly examined, as will be seen from 

 the series of figures on the plates the object being to give a general 

 idea of the structural changes of these cells. The explanations 

 of each of these figures will make the pith of this chapter, as by so 

 doing I believe the description could be much simplified and its 

 understanding facilitated as much as possible. Thus, I shall ap- 

 preciate very much if the reader will constantly refer to those 

 figures while reading. 



(1). The syncytium cell-layer (figs. 1 to 12) 



As is well known, the syncytium layer is the epithelium which 

 covers the surface of the villi, and the lack of boundaries between 

 the cells is a feature of this layer. And it is also well known that 

 within this layer there are several kinds of nuclei, differing in 

 size and form and scattered here and there, besides dark-colored 

 granular bodies and a great number of vacuoles which occasion- 

 ally appeared in it. Its surface is covered with a brush-like 

 border. This layer is generally well developed in the early stages 

 of pregnancy, but in the second half of pregnancy it becomes 

 thinner and looks much like an endothelium, so that, when examin- 

 ing its minute structure, it will be necessary to do so before the 

 fourth month of pregnancy. Figure 1 shows that part of the 

 anchoring vilh which extends deeply into the decidua, while all 

 the other plates show the different parts of the surface of the 

 ordinary villi. 



In figure 1 the syncytium presents a homogeneous proto- 

 plasmic layer generally dark-colored and contains an extremely 

 large quantity of plastosomes (mitochondria). They are of 

 different shapes, but mostly are rod-shaped or bacteroid and of 

 different lengths, the longer ones being slightly curved. They 

 arrange themselves in groups rather than being equally distrib- 

 uted over the layer, and in some places some of them point in 

 the same direction, while others point in various directions, 



