Final answer:
The protective structure that forms around an embryo is called the placenta. It provides oxygen, nutrients, and protection to the developing fetus.
Step-by-step explanation:
The protective structure that forms around an embryo is called the placenta. The placenta is an organ that develops during pregnancy and provides oxygen and nutrients to the fetus while removing waste products. It also acts as a barrier, protecting the embryo from harmful substances and infections.
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