In human sperm , nebenkern refers to

Options

A. Post acrosomal sheath
B. Mitochondrial spiral
C. Proximal centriole
D. Axial filament

Answer

To solve the question "In human sperm, nebenkern refers to," we will analyze the options provided and determine the correct answer step by step.

### Step 1: Understand the term "nebenkern"
- The term "nebenkern" is derived from German, meaning "adjunct nucleus." In the context of human sperm, it refers to a specific structure associated with the mitochondria.

**Hint:** Look for terms that relate to mitochondria or energy production in sperm.

### Step 2: Analyze the options
1. **Postacrosomal sheath**: This is a structure located in the sperm but does not refer to the nebenkern. Thus, this option is incorrect.

**Hint:** Consider what the postacrosomal sheath does in relation to the sperm's function.

2. **Mitochondrial spiral**: This option refers to the arrangement of mitochondria in the sperm. The nebenkern is indeed associated with the mitochondrial structure in sperm, making this option the correct answer.

**Hint:** Think about how mitochondria are arranged in sperm and their role in energy supply.

3. **Proximal centriole**: This structure is involved in the organization of the sperm's tail but does not relate to the nebenkern. Therefore, this option is incorrect.

**Hint:** Recall the function of centrioles in cell division and movement.

4. **Axial filament**: This structure is part of the flagellum of the sperm and is not related to the nebenkern, making this option incorrect as well.

**Hint:** Consider the role of axial filaments in sperm motility.

### Step 3: Conclusion
After analyzing all the options, we conclude that the correct answer is **mitochondrial spiral**, as it accurately describes the nebenkern in human sperm.

### Final Answer:
**Mitochondrial spiral (Option 2)**

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