The |umbilical cord| links the |embryo| to the |placenta| and is formed at the same time as the |placenta|. While ~blood~ vessels are forming in the chorionic villi, others are forming in the inner cell mass within the |embryo|. Three ~blood~ vessels emerge from the |embryo| and join with those of the developing |placenta|. These form the basis of the |umbilical cord|, which is attached to the |embryo| at the navel.
