A textbook of obstetrics . Fig. 96.—Metastasis of syncytial cancer in liver, showing cells from Langhans layerand true syncytial cells. 1 V. , •• Monatschr. f. Geburtsh, u. Gyn., Bd. iv, II. 3, p. 229. 132 PREGNANCY. THE UMBILICAL CORD. The early development of the umbilical cord, or the formationof the allantois, has been studied upon the lower animals, as inall the human embryos observed the connection between theembryo and the chorion was already established. Indeed, accord-ing to Mis, the human embryo is from the first in connection withthe periphery of the ovum. Very early, therefore,
A textbook of obstetrics . Fig. 96.—Metastasis of syncytial cancer in liver, showing cells from Langhans layerand true syncytial cells. 1 V. , •• Monatschr. f. Geburtsh, u. Gyn., Bd. iv, II. 3, p. 229. 132 PREGNANCY. THE UMBILICAL CORD. The early development of the umbilical cord, or the formationof the allantois, has been studied upon the lower animals, as inall the human embryos observed the connection between theembryo and the chorion was already established. Indeed, accord-ing to Mis, the human embryo is from the first in connection withthe periphery of the ovum. Very early, therefore, in embryonallife there may be observed a sac-like projection from the posteriorend of the intestinal tract, which, at first solid, but later contain-ing a canal, grows outward and backward, owing to the presenceof the large umbilical vesicle anteriorly, until it comes in contactwith the periphery of the ovum. Within this sausage-shaped l. Fig. 97.—A, Umbilical arteries forming spirals (/, ?) around the vein ; con-strictions indicating the presence of folds ((/, e); circular folds (a, e)\ lateralopenings showing the arterial walls; B, vein opened upon the side showing a con-striction (b) corresponding to an interior valve (e); semilunar valves (,, d% <);C, section of vein and arteries showing valve of vein (a), a semilunar arterial valve(/;), and a circular arterial valve {<) (Tarnier et Chantreuil). projection are blood-vessels, which are carried with its growthto the periphery of the ovum, where they enter the villi of thechorion in the manner already described. Becoming reducedto two arteries and a vein within the allantois itself, they con-stitute the vessels of the umbilical cord, which are destinedt<» carry the blood of the fetus to the placenta for aeration andnourishment, the two arteries conveying dark, venous blood ;the vein returning bright, oxygenated blood, resembling in thisrespect the pulmonar
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Keywords: ., bookcentury1800, bookdecade1890, bookidtex, booksubjectobstetrics
