Umbilical cord carries oxygenated, nutrient-rich blood to the fetus, and two arteries that carry deoxygenated, nutrient-depleted blood away. Occasionally, only two vessels (one vein and one artery) are present in the umbilical cord. This is sometimes related to fetal abnormalities, but it may also occur without accompanying problems. It is unusual for a vein to carry oxygenated blood and for arteries to carry deoxygenated blood (the only other examples being the pulmonary veins and arteries, connecting the lungs to the heart). However, this naming convention reflects the fact that the umbilical vein carries blood towards the fetus's heart, while the umbilical arteries
Blood-vein "Atriplex". It overwinters as a larva. Blood-vein The blood-vein, ("Timandra comae") is a moth of the family Geometridae. It has a scattered distribution in western and central Europe north of the Alps. In the British Isles the distribution is patchy outside southern England and Wales. In far eastern Europe – east of a line running roughly from Finland through Estonia –, it is replaced by its sister species "Timandra griseata". The species were split in 1931, only to be subsequently re-merged by most authors. But since 1994, new research has come out in favour of treating them as distinct species.