The structure that connects an embryo to the placenta and nourishes it is called the umbilical cord.

Here's a breakdown:

* Umbilical Cord: This is a flexible, rope-like structure that contains blood vessels that transport oxygen-rich blood and nutrients from the placenta to the embryo, and waste products from the embryo back to the placenta to be removed by the mother's system.

* Placenta: This organ is attached to the uterine wall and acts as the interface between the mother's and the embryo's circulatory systems. It provides oxygen and nutrients to the embryo and removes waste products.

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