Read the following statements and choose incorrect one.

Options

A. Embryo at 16 celled stage is known as morula.
B. Acrosomal reaction of sperm help in compatibility check.
C. During fertilization, a sperm comes in contact with zona pelluciada layer of sperm
D. During entry into the ovum, acrosome of sperm releases hyaluronidase

Answer

To solve the question of identifying the incorrect statement from the provided options regarding human reproduction, we can follow these steps:

### Step-by-Step Solution:

1. **Analyze the First Statement:**
- **Statement:** "Embryo at 16 cell stage is called morula."
- **Evaluation:** This statement is correct. The morula is indeed the 16-cell stage of the embryo, characterized by a solid mass of cells.

2. **Analyze the Second Statement:**
- **Statement:** "Acrosomal reaction of sperm helps in compatibility check."
- **Evaluation:** This statement is also correct. The acrosomal reaction is crucial during fertilization as it enables the sperm to penetrate the zona pellucida and fuse with the ovum.

3. **Analyze the Third Statement:**
- **Statement:** "During fertilization, the sperm comes in contact with zona pellucida layer of sperm."
- **Evaluation:** This statement is correct. The sperm indeed comes into contact with the zona pellucida, which is the outer layer of the ovum, during the fertilization process.

4. **Analyze the Fourth Statement:**
- **Statement:** "During entry into the ovum, acrosome of sperm releases hyaluronidase."
- **Evaluation:** This statement is correct. The acrosome reaction involves the release of enzymes, including hyaluronidase, which helps the sperm penetrate the zona pellucida.

5. **Identify the Incorrect Statement:**
- After evaluating all statements, the third statement is incorrect because it incorrectly states that the sperm comes in contact with the "zona pellucida layer of sperm," which is a misrepresentation. The sperm contacts the zona pellucida of the ovum, not a layer of sperm.

### Final Answer:
The incorrect statement is: "During fertilization, the sperm comes in contact with zona pellucida layer of sperm."

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