On the structure of the human placenta and its connection with the uterus

In the year 1780 Mr. John Hunter presented a paper to the Royal Society, in which he laid claim to the discovery of the true structure of the placenta, and of its vascular connections with the uterus. From the appearances which he observed in a preparation of the gravid uterus, after both the veins and arteries had been injected, and a longitudinal incision made through the anterior parietes of the uterus where the placenta adhered to its internal surface, he was led to conclude that the arteries which are not immediately employed in conveying nourishment to the uterus go on towards the placenta, and proceeding obliquely between it and the uterus, pass through the decidua without ramifying; and that just before entering the placenta, after making two or three spiral turns, they open at once into its spongy substance. The corresponding veins he represents as commencing from the spongy substance of the placenta by wide mouths, and after passing obliquely through the decidua, entering the substance of the uterus and immediately communicating with the proper veins of that organ. Dr. William Hunter’s description of the same vessels accords with that of his brother. He regards the placenta as consisting of two distinct parts, namely, an umbilical portion which belongs to the foetus, and a uterine portion, which belongs to the mother, each having its peculiar system of arteries and veins; and he supposes that while, in the fœtal portion, the arteries and veins form continuous canals, these two sets of vessels communicate, in the uterine portion, by the intervention of cells, into which the arteries terminate, and from which the veins begin. The subject was afterwards investigated by Noortwych, Rœderer, and Haller, but without any satisfactory result; and the doctrines laid down by the Hunters were generally acquiesced in by subsequent anatomists.