**Cytoplasm surrounding mitochondria in the middle piece of sperm is called manchette**.

The manchette is a specialized structure found in the middle piece of the sperm, which is located between the head and the tail. It is composed of cytoplasm and surrounds the mitochondria in this region. The manchette plays a crucial role in the development and function of sperm cells.

**Function of the Manchette:**

1. **Sperm Tail Formation:** The manchette is involved in the formation of the sperm tail, also known as the flagellum. The tail is essential for sperm motility, which is required for successful fertilization. The manchette helps in the assembly and organization of the microtubules that make up the flagellum.

2. **Transport of Cellular Components:** The manchette acts as a conduit for the transport of various cellular components from the head to the tail of the sperm. This includes proteins, RNA, and other molecules necessary for sperm development and function. The manchette facilitates the transport of these components along microtubules within its structure.

3. **Mitochondrial Distribution:** Mitochondria in the middle piece of the sperm are responsible for providing the energy required for sperm motility. The manchette helps in the proper distribution of mitochondria throughout the sperm tail, ensuring an adequate energy supply for efficient movement.

4. **Structural Support:** The manchette provides structural support to the developing sperm cell. It helps in shaping the sperm tail and maintaining its integrity. The organization and arrangement of microtubules within the manchette contribute to the overall structure and stability of the sperm cell.

**Other Options Explained:**

- **Centroplasm:** Centroplasm refers to the central portion of the cell, which contains the nucleus and other organelles. It is not specifically related to the cytoplasm surrounding mitochondria in the middle piece of sperm.

- **Microplasm:** Microplasm is not a recognized term in biology. It may be a typographical error or a term specific to a certain context or field.

- **Acrosome:** The acrosome is a structure found at the tip of the sperm head. It contains enzymes that are released during fertilization to facilitate the penetration of the egg's protective layers. It is not directly related to the cytoplasm surrounding mitochondria in the middle piece of sperm.

acrosome see the diagram of sperm in class 12 ncert textbook