A textbook of obstetrics . ng 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 pulmonary arteries and vein. Surrounding the blood-vessels of the cord is a peculiar gelatinous substance, furnishingthe vessels the most perfect protection possible- under the cir-cumstances (the so-called gelatin of Wharton), derive
A textbook of obstetrics . ng 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 pulmonary arteries and vein. Surrounding the blood-vessels of the cord is a peculiar gelatinous substance, furnishingthe vessels the most perfect protection possible- under the cir-cumstances (the so-called gelatin of Wharton), derived fromthe outer layers of the amnion and tin- allantois, both in their 1 A//(m , a sausage. THE UMBILICAL CORD. *33 turn being derived from the median layer of the blastodermicmembrane. As the amniotic cavity becomes distended theamnion is pushed out on all sides until it meets in front of the em-bryo, and surrounds the cord like the finder of a glove, at thesame time inclosing the already atrophied umbilical vesicle, the. Fig. 98.—A, Section of the navel: C, Outer covering with blood-vessels ; ,umbilical vein; </.//?., , umbilical artery; , omphalic duct; u., remnant of theurachus. 13, Section of the cord : ., Sheath of the cord. Other lettering as in A. ductus omphalicus, and the pedicle of the allantois. That por-tion of the allantois that remains within the abdominal cavity ofthe fetus forms the bladder and urachus. The umbilical cord atterm measures about cm. (20 in.) in length and about cm. (1/3 to y2 in.) or more indiameter, the latter measurementbeing irregular, from the fact thatthe arteries are coiled around thevein, usually from right to left,giving a twisted appearance tothe cord, and also because thegelatin of Wharton is depositedirregularly, being in some placesquite thick, and forming thus theso-called false knots of the the arteries and theveins of the cord have walls ofalmost the same thickness, andboth are provided
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Keywords: ., bookcentury1800, bookdecade1890, bookidtex, booksubjectobstetrics
