Lectures on the comparative anatomy of the placenta : first series / delivered before the Royal College of Surgeons of England, June, 1875, by Wm. Turner.

  • William Turner
Date:
1876
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Licence: Public Domain Mark

Credit: Lectures on the comparative anatomy of the placenta : first series / delivered before the Royal College of Surgeons of England, June, 1875, by Wm. Turner. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    branes into this comu, and the cavity seemed as if almost obliterated by the thickening of the raucous membrane. Hyrax agrees, therefore, with Felis not only in the form and structure of the placenta, but in the large size of the sac of the allantois; it differs in the condition of the umbilical vesicle, which disap- pears in Hyrax apparently at an early period, but remains in Fdis to the end of utero-2:estation. Elephant.—No observations have been recorded on the structure of the uterine mucosa in the gravid Elephant, but Prof. Owen has described and figured' the foetal membranes at about the mid-period of utero-gestation. The chorion was encompassed at its middle by an annular placenta, 2 ft. 6 in. in circumference, varying from 3 to 5 in. in breadth, and from 1 to 2 in. in thickness : The placenta presents the same spongy texture and vascularity as does the annular placenta of the Hyrax and of the Gurrdvora; but the capillary filaments or villosities enclosing the foetal vessels enter into its formation in a larger proportion, and are of a relatively coarser character. The greater pai-t of the outer convex surface of the placenta is smooth: the rough surface, which had been torn from the maternal or uterine placenta, exposed the fcetal capillaries, and occupied chiefly a narrow tract near the middle line of the outer surface. A thin brown deciduous layer is continued from the borders of the placenta, for a distance varying from one to three inches, upon the outer surface of the chorion. In addition, at each of the poles of the chorion was a villous and vascular subcircular ])atch, between two and three inches in diameter, the villi being short, ith of a line in diameter, or less. The bag formed by the mucous or unvascular layer of the allan- tois is of considerable size, is continued from the base of the umbilical cord, so exi^anding between the chorion and amnios as to prevent any part of the amnios attaining the inner surface of the placenta. The allantois divides, where the amnios begins to be reflected upon it, into three sacculi ; one extends over the inner surface of the anmdar placenta and a little Avay into one end of the choiion: a second extends into the opposite end of the chorion, it there bends round toward the placenta, and its apex adheres at that part to the fii-st division of the allantois : the third prolongation subdivides into two smaller cavities, each terminating in a cul-de-.sac, encompassing, and closely attached to the primary divisions of the umbilical vessels. This specimen is preserved in the Museum of your College, and through the courtesy of Professor Flower I have been J Phil. Trans. 1857, p. 3i7, and Comp. Anat. of Vert. in. 740.