350 



HUMAN UTERUS AND FCETAL APPENDAGES. 



offer a fibrillar structure (Fig. 208, A), and when that is the ease we can no longer 

 make out a distinct mesothelial layer. At other times the more or less homo- 

 geneous matrix can be seen through the whole thickness of the amnion (Fig. 208, 

 B), and when this is the case the mesothelium, a, can be readily identified. 



In surface views the amniotic ectoderm is seen to consist of more or less 

 regularly distributed nuclei with cell-bodies connecting with one another by 

 intercellular bridges of protoplasm (Fig. 209). The nuclei, nu, are relatively 

 large, rounded, and with distinct outlines. They have a more or less well-marked 

 internuclear network with thickened nodes and a small number of deeply stained 



Fig. 208. — Two Sections of the Human 

 Amnion. 



A, From an embryo of eiyht months; 13, at term. 

 eel, Ectoderm, mes, Mesoderm, a, Meso- 

 thelium. X 34° diams. 



pi. 



P<-.. 



nu. 







Fig. 209.— Surface View of the Human Amniotic 



Epithelium of the Fourth Month. 

 //, Protoplasm, pr, Intercellular processes, nu, Nu- 

 cleus. X I22 S <liams. 



granules which are probably chromatin. Each nucleus is surrounded by a cell- 

 body, pi, and the adjacent cell-bodies are separated from one another by clear 

 spaces which are crossed by threads of material, pr, stretching as bridges between 

 the neighboring cells. The protoplasm is vacuolated. The whole picture thus 

 leads to the view that the epithelium is a sponge-work of protoplasm somewhat 

 condensed around each nucleus. As regards the mesoderm, it is very difficult to 

 obtain clear pictures of the cells, though the nuclei can be readily observed. 

 They vary greatly in appearance, being sometimes fairly regular and uniform, 



