Henry Gray (1825–1861). Anatomy of the Human Body. 1918.
FIG. 458
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| Diagram of the vascular channels in a human embryo of the second week. (After Eternod.) The red lines are the dorsal aortæ continued into the umbilical arteries. The red dotted lines are the ventral aortæ, and the blue dotted lines the vitelline veins. |