Observations on certain parts of the animal oeconomy. Inclusive of several papers from the Philosophical transactions, etc / by John Hunter ... With notes by Richard Owen.
- John Hunter
- Date:
- 1840
Licence: Public Domain Mark
Credit: Observations on certain parts of the animal oeconomy. Inclusive of several papers from the Philosophical transactions, etc / by John Hunter ... With notes by Richard Owen. Source: Wellcome Collection.
110/494 page 102
![iit” & 102 | HUNTER ON THE ANIMAL G:CONOMY. though the uterus is appropriated for the support of the foetus, as_ CY nourishment as the nterus; and this, I believe, is peculiar to genera- tion. This prompts me to make the following observations upon the different situations of the foetus in extra-uterine cases, which are extraordinary, happen seldom, and when they do occur are often attended with so many hindrances to critical investigation, as. hardly to allow of thorough or satisfactory information. Such cases are readily distinguished from. natural ones by the uterus being found entire and empty ; and they may be divided into three different kinds, according to the situation of the foetus in the ovarium, Fallopian tube, or in the cavity of the abdomen. From a want of the appearances which usually attend the natural process, the investigation of extra-uterine cases is attended with considerable difficulty. For where uncommon actions have taken place, as well as in cases of disease, the natural texture of the parts cellular tissue which everywhere surrounds and supports the foetal capillaries. On comparing these appearances with my first dissection, I perceived that the uterine vein, opposite the mouth of which I had supposed the decidua to be want- ing, and whose orifice was in contact with the capillaries of the placenta, was in reality one of the oblique decidual canals, returning the blood from the cellular substance of the placenta into the uterine vein, its continuity with which had been preserved. The continuation of the uterine veins into decidual canals was much more dis- tinct in those which terminated near the circumference of the placenta; and here the irregular portions of injection, which filled the canals as far as the surface of the placenta, were evidently circumscribed, by distinct parietes, and not the result of confused extravasation: the injection from the decidual canals had passed into the large interlobular spaces, or maternal sinuses of the placenta, and thence had become diffused, generally for the extent of an inch, into the spongy or cellular texture of the placenta. The uterine arteries in this case had not been injected, but were easily trace- able passing through the external and placental decidua, as far as the internal surface of the latter, and apparently opening or being lost on the spongy surface of the placenta. With reference to preparations of vascular and cellular structures like the pla- centa, it is not easy to enforce conviction from the appearances they present, in consequence of the difficulty of distinguishing between natural and accidental extravasation. Having, however, carefully compared the Hunterian preparations with the results of my own examinations of the gravid uterus at the full period, 1 now believe they all fully bear out Mr. Hunter’s general view, viz., that the maternal blood is diffused, by means of the tortuous arteries, into the spongy cellular sub- stance of the placenta, where it bathes the capillaries of the fetal circulation, ' and is returned by the oblique decidual adventitious sinuses and channels into the orifices of the uterine veins. Thus the placental intercommunication between the feetus and mother, in the human subject and Quadrumana, is earried on by the contact of the foetal capillaries with maternal extravasated blood ; while in the Ruminants, the mare, and the sow,? it takes place by the apposition of capillaries to capillaries, and the two parts of the placenta, viz., foetal and maternal, can be separated. In the Ferz and Rodentia there appears tc bean intermediate structure. ] 4 [In the last two examples the placenta may be said to be diffused over nearly the whole surface of the chorion.]](https://iiif.wellcomecollection.org/image/b33292292_0110.jp2/full/800%2C/0/default.jpg)
