Cord-like structure connecting the fetus with the placenta and housing the umbilical artery and umbilical vein that carry nutrients from the mother and remove wastes from the fetus.
Source: PAC, 2016, 88, 713. 'Glossary of terms used in developmental and reproductive toxicology (IUPAC Recommendations 2016)' on page 817 (https://doi.org/10.1515/pac-2015-1202)