40 Dr. T. W. Eden. 



4i The Occurrence of nutritive Fat in the Human .Placenta. A 

 Preliminary Communication." By THOMAS WATTS EDEN, 

 M.D., M.R.C.P. Communicated by Dr. PYE SMITH, F.R.S. 

 Received April 23, Read May 7, 1896. 



(From the Laboratories of the Conjoint Board of the Royal Colleges of Physicians 

 (Lond.) and Surgeons (Eng.)). 



Recently, while examining specimens of ripe placentae for fatty 

 degeneration, I was struck by the regularity of the occurrence of fat 

 in this structure, and especially by the nature and extent of its dis- 

 tribution. I was then led to examine a series of specimens taken at 

 different periods of gestation, with the result that a free deposit of 

 fat was found in ten different placentae, all of which I believe to be 

 non-pathological, and ranging practically through, all periods of 

 gestation, from the sixth week up to term. 



The method employed for the demonstration of this fat, was to take 

 slices from different parts of the placenta, and harden them for a few 

 days in Muller's fluid; then to transfer thin strips, not exceeding one- 

 third of an inch in thickness, to Marchi's fluid (1 per cent, solution 

 of osmic acid 1 part, Muller's fluid 2 parts) for a week. The pieces 

 were then embedded in paraffin, cut with a rocking microtome, and 

 stained lightly with saffranine, eosine, or logwood and cosine, pr 

 mounted unstained. By this process the fat is completely blackened, 

 while the other tissues retain their normal staining reactions, so 

 that the outlines of the fat-containing cells can be distinctly made 

 out. 



By this method I have been able to demonstrate the constant 

 occurrence of fat in certain well-defined regions of the human 

 placenta. 



In the young human placenta, the epithelial covering of the villi 

 consists of two layers, a superficial, nucleated, plasmodial layer, and 

 a deep cellular layer. In a six weeks' ovum I found fat in the form 

 of minute droplets in both these layers, but much more abundantly in 

 the former than in the latter. These fat droplets show comparatively 

 little variation in size, and they remain discrete, showing little or no 

 tendency to form larger droplets by fusion ; they are confined to the 

 perinuclear protoplasm, and are never found in the nuclei, which 

 remain unaltered in number, form, and arrangement. The stroma of 

 these villi contains here and there a trace of fat, but it is apparently 

 healthy, and is furnished with well-formed wide capillaries filled 

 with blood. The villi are, in fact, to all appearance healthy. Every 

 villus does not show this deposit of fat, but it is present in very large 

 numbers of them ; in every field of the microscope several villi 



