SECRETOEY FUNCTIONS IN HUMAN PLACENTA 493 



were always taken from the decidua vera only, at every stage of 

 pregnancy, by means of scratching out. x\ll these pieces of tissues 

 were so taken that they should not exceed a cube 3 mm. in size, 

 and immediately after cutting they were dipped in the newly 

 prepared fixing solutions. For the latter I have used: 1, 

 Altmann's fluid of potassium bichromate and osmium tetroxide; 

 2, Flemming's solution modified by Benda; 3, Flemming's solu- 

 tion modified by Meves; 4, Levi's mixture of formol, osmic acid, 

 potassium bichromate, and corosive sublimate; 5, Luna's mixture 

 of formol, potassium bichromate, and glacial acetic acid. Each 

 of the pieces was then treated in the usual manner being imbedded 

 in paraffin and cut in sections of 3 to 4 n. And as a treatment prior 

 to staining, Rubaschkin's method has been applied in a great 

 majority of cases. For staining I have employed: 1, Altmann's 

 method of acid fuchsin and picric acid; 2, Heidenhain's iron-alum- 

 haematoxylin, and, 3, Benda 's alizarin-crystal-violet method, 

 etc. All the methods which I have adopted, the fixation with 

 Levi's mixture, and the staining with iron-alum-haematoxylin 

 have been found to be comparatively successful. 



MY OWN OBSERVATIONS 



The chorionic vilh, which are a main component of the placenta' 

 consist of: 1) the syncytium cell-layer; 2) the Langhans' cells' 

 and, 3) the ' Stromazellen, ' being cells in the stroma of vilh? 

 while the components of the decidua serotina and the decidua 

 vera chiefly consist of, 4) the decidual cells and, 5) the epithe- 

 lium of the uterine gland. In the present chapter I intend to 

 give a detailed account, mainly from the histological standpoint, 

 of these important tissue components, or cell groups, especially 

 as they appear in the different stages of pregnancy. However, 

 since the structure of all kinds of cells varies even in the same 

 stage of pregnancy and in the same group of cells, it would be a 

 difficult task indeed to explain clearly the correlations existing 

 between the minute structural changes of these cells, or cellular 

 groups, and their functional significance. Therefore, I have 



