A treatise on the science and practice of midwifery . f small intestine. The capillaries are the terminalramifications of the umbilical arteries and veins, which, after reachingthe site of the placenta, divide and subdivide until they at last form animmense number of minute capillary vessels, with their convexities look-ing toward the maternal portion of the placenta, each terminal loopbeing contained in one of the digitations of the chorion villi. Eacharterial twig is accompanied by a corresponding venous branch, whichunites with it to form the terminal arch or loop (Fig. 59). The foetalblood
A treatise on the science and practice of midwifery . f small intestine. The capillaries are the terminalramifications of the umbilical arteries and veins, which, after reachingthe site of the placenta, divide and subdivide until they at last form animmense number of minute capillary vessels, with their convexities look-ing toward the maternal portion of the placenta, each terminal loopbeing contained in one of the digitations of the chorion villi. Eacharterial twig is accompanied by a corresponding venous branch, whichunites with it to form the terminal arch or loop (Fig. 59). The foetalblood is carried through these arterial twigs to the villi, where it comesinto intimate contact with the maternal blood, in consequence of theanatomical arrangements presently to be described ; but the two do notdirectly mix, as the older physiologists believed, for none of the mater- CONCEPTION AND GENERATION. 113 nal blood escapes when the umbilical cord is cut, nor can the minutestinjections through the foetal vessels be made to pass into the maternal. Placental Villus, greatly magnified. (After Joulin.) 1, 2, Placental vessels, forming terminal loops. 3. Chorion tissue, forming external -walls of villus. 4. Tissue surrounding vessels. vascular system, or vice versa. In addition to the looped terminations ofthe umbilical vessels, Farre and Schroeder van der Kolk have described Fig. 60.
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectobstetrics, bookyear1
