AND ITS CONNEXION WITH THE UTERUS. 
63 
In the Museum of the Royal College of Surgeons of London, there is a pre- 
paration of the uterus with the placenta adhering to the inner surface, which 
is supposed to have been put up by Mr. Hunter himself nearly fifty years ago. 
The vessels both of the uterus and placenta have been filled with injection, and 
the parietes of the uterus, placenta and membranes, have all been divided by 
a vertical section into two nearly equal portions. By permission of the Board 
of Curators, I have been enabled to examine one of these portions, and to 
have a drawing of it made. In the interstices of the muscular fibres I ob- 
served the veins of the uterus, which ran in great numbers towards the part 
where the placenta adhered. They were of an oval form, their long axes 
being in the long axis of the uterus. The muscular fibres ran longitudinally 
from the fundus to the os uteri. (Plate II.) 
The deciduous membrane was everywhere covered with minute, tortuous 
blood-vessels proceeding from the inner surface of the uterus, and filled with 
injection. There was no appearance of vessels of any magnitude passing be- 
tween the inner surface of the uterus and placenta; but flattened portions of 
injection were observed in this situation, having in many parts the form of 
thin layers, which had obviously escaped from the orifices of the uterine veins. 
Elsewhere the injection had lacerated the deciduous membrane, and formed 
deposits in the vascular part of the placenta. 
The facts which have now been stated warrant, I think, the conclusion, that 
the human placenta does not consist of two parts, maternal and foetal, that no 
cells exist in its substance, and that there is no communication between the 
uterus and placenta by large arteries and veins. The whole of the blood sent 
to the uterus by the spermatic and hypogastric arteries, except the small por- 
tion supplied to its parietes and to the membrana decidua by the inner mem- 
brane of the uterus, flows into the uterine veins or sinuses, and after circulating 
through them, is returned into the general circulation of the mother by the 
spermatic and hypogastric veins, without entering the substance of the pla- 
centa. The deciduous membrane being interposed between the umbilical 
vessels and the uterus, whatever changes take place in the foetal blood, must 
result from the indirect exposure of this fluid, as it circulates through the pla- 
centa, to the maternal blood flowing in the great uterine sinuses. 
