



The Occurrence of nutritive Fat in the Human Placenta. 41 



containing fat may be found. The amount of fat also varies con- 

 siderably. 



In a young ovum the plasmodial layer of the villi shows great pro- 

 liferative activity ; it throws out numerous club-shaped processes or 

 buds, which represent the first stage in the development of new 

 villi. These buds very frequently contain large numbers of minute 

 fat droplets. I believe that this is a point of very great importance, 

 showing, as it does, that the deposit of fat occurs in actively growing 

 tissues of undoubted vitality. 



]n the ripe placenta the proliferation of the plasmodial layer has 

 ceased, and degenerative changes are present in scattered regions. 

 But, of course, the great majority of the villi retain their vitality, 

 and in these villi a free deposit of fat is present, showing the same 

 distribution and characters as in the young placenta. 



I have also found a similar deposit of fat in the serotina. The six 

 weeks' ovum, above referred to, showed very many decidual cells 

 containing minute, discrete droplets of fat in the perinuclear proto- 

 plasm. A placenta of the sixth month also showed an abundant fat 

 deposit in' the same region. At term, the serotina shows many 

 degenerative changes, and although it contains fat, it may well be 

 doubted whether, at this period, this is a physiological deposit. 



The placenta, indeed, appears to be a storehouse of nutritive fat, 

 just as is the liver. This appears to throw some light on what has 

 long been one of the problems of foetal physiology, viz., the source 

 frcm which the foetus obtains its supplies of fat. Diffusible substances 

 such as sugar, salts, peptones, &c., were supposed to pass by osmosis 

 from the maternal blood in the inter- villous spaces, to the foetal blood 

 in the villi. But this could not be assumed of indiffusible substances 

 such as fat. The truth would seem to be that fat is deposited from 

 the maternal blood in the epithelium of the villi, and stored up there 

 by the foetal tissues for their use. No great accumulation of fat 

 occurs, as it appears to be from time to time absorbed and disposed 

 of by the foetal circulation. It is, however, not altogether clear how 

 si deposit of fat in the decidual cells can be made available for the 

 purposes of foetal nutrition. 



Since finding this fat deposit in the human placenta, I have begun 

 a series of comparative observations upon the placentae of other 

 mammals. Up to the time of writing, I have examined two rabbits' 

 placentae, one from an early, and the other from a late, period of 

 gestation. In both there was a marked deposit of fat, chiefly in the 

 superficial glandular layer of the maternal placenta, but also, though 

 to a less extent, in the processes of the chorionic mesoblast, which 

 form the homologues of the villi of the human placenta. 



The process appears to correspond closely to that observed by 

 Mr. George Brook, in the transmission of fat from the yolk to 



