Final answer:
The protective structure that forms around an embryo is called a blastocyst.
Step-by-step explanation:
The name for the protective structure that forms around an embryo is blastocyst. A blastocyst is an early stage of development in mammals where a hollow ball of cells is formed, enclosing the inner cell mass which will later develop into the embryo. The blastocyst provides protection for the developing embryo and allows it to implant into the uterus wall.
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