Complete the statement:
In Cockroach, blood vessels open into spaces called _____________ .

Explanation

To complete the statement, we need to identify the specific term that describes the spaces into which the blood vessels of a cockroach open.

1. **Understanding the Circulatory System of Cockroach**: Cockroaches have an open circulatory system, which means that their blood (hemolymph) is not entirely contained within blood vessels. Instead, it flows freely in body cavities.

2. **Identifying the Spaces**: In an open circulatory system, blood vessels open into spaces that are not enclosed. These spaces allow the blood to bathe the organs directly.

3. **Terminology**: The specific term used to describe these spaces in which the blood vessels open is "hemocoel."

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