II. 



PLACENTA. 



This account has been furnished by Dr. Reitz, of St. Petersburg!!, 

 who made the investigations bearing upon the subject under my 

 directions. STRICKER. 



THE placenta of the human subject is composed of a maternal 

 and of a foetal portion; but from the fourth month of pregnancy 

 these are intimately fused together. The maternal portion, the 

 placenta uterina, which upon the average is from a quarter to 

 half a millimeter thick, is composed chiefly of large cellular 

 elements. The cells are very variously formed, and are for 

 the most part thickly granulated, and exhibit a distinct large 

 spheroidal nucleus, with one or several nucleoli ; occasionally 

 two or more nuclei are present ; many cells are provided 

 with one or several processes of various lengths. Between 

 these cells, large vesicles, with numerous nuclei in their 

 interior, are, according to Kolliker, to be here and there 

 found.* 



The cells are usually arranged so closely that they form 

 nearly the whole thickness of the placenta uterina ; but they 

 are frequently arranged also in groups, and sometimes also in 

 quite an isolated manner, imbedded in the matrix, which 

 appears as a fibrous tissue, or in parts as a hyaline finely gra- 

 nular mass. Between these cells If found colossal encapsuled 

 cells with large vesicular nuclei and nucleoli. In consequence 

 of their coarsely granular contents, nuclei and nucleoli, as 



* Kolliker, Entwickelungsgeschichte, 1861. 



t Sitzungsberichte d. K. Akad. der Wissenschaften, Mai-Heft. Wien,1868. 



