A Reference handbook of the medical sciences embracing the entire range of scientific and practical medicine and allied science . he first formedarteries, n a m e 1 y,the omphalo-mesen-t e r i c s, connectedwith the yolk sac,and the urabilicals,connected with theallantois. Soon af-ter these are formedthe veins within thebody of the embryodevelop, the firstones being the an-terior cardinals, orinternal jugularsand the inferiorcardinals, the lat-ter draining theblood from the cau-dal ])ortion of thebody. An anteriorand a posterior car-dinal of each sideunite to form theductus two duc
A Reference handbook of the medical sciences embracing the entire range of scientific and practical medicine and allied science . he first formedarteries, n a m e 1 y,the omphalo-mesen-t e r i c s, connectedwith the yolk sac,and the urabilicals,connected with theallantois. Soon af-ter these are formedthe veins within thebody of the embryodevelop, the firstones being the an-terior cardinals, orinternal jugularsand the inferiorcardinals, the lat-ter draining theblood from the cau-dal ])ortion of thebody. An anteriorand a posterior car-dinal of each sideunite to form theductus two ducts, oneon either side, passtransversely towardthe median line andopen into the sidesof the sinus veno-sus. The omphalomesenteric veins coming from theyolk sac and the utiibilicals from the allantois join thesinus venosus at a slightly earlier date than do the Cuvi-erian ducts. At a later stage we shall see how tliisprimitive arrangement is modified to form the adultcondition. The yolk sac in this embryo is somewhatconstricted along its attachment, leaving pockets of en-toderm connected with it tliat lie iu the head and tail. Fig. •>U4.—Reconstruction of Embryo Long. (Enlarged about 25 diameters.)al, Allantois; am, amnion; B, bellystalk ; ch, chorion ; )i, heart.; nis. nieso-dermic somite; ot^, oral fossa; ph. pha-rynx ; r, chorionic villi; 1, yolk-sac.(After Eternod.)
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Keywords: ., bookauthorbuckalberthalberthenr, bookcentury1900, bookdecade1900
