Point of sperm enetyr forms

Options

A. Axis of cleavage
B. Grey crescent
C. Doresal lip of blastopore
D. Centre of embryo rotation.

Answer

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks about the point of sperm entry during fertilization and its significance in embryonic development.

2. **Identifying the Gametes**: Recognize that the female gamete is the egg and the male gamete is the sperm. Fertilization occurs when the sperm enters the egg.

3. **Sperm Entry and Axes Formation**: When the sperm penetrates the egg, it establishes a point of entry that is crucial for the subsequent development of the embryo. This point of entry is significant because it helps define the axes of the developing embryo.

4. **Dorsoventral Axis**: The point of sperm entry creates a dorsoventral axis in the embryo. This means that the dorsal (back) and ventral (belly) sides of the embryo are established based on where the sperm entered.

5. **Cleavage and Development**: Following fertilization, the area around the sperm entry point becomes the site of cleavage, which is the process of cell division that occurs after fertilization. This is referred to as the "excess of cleavage."

6. **Choosing the Correct Option**: Based on the explanation, the correct answer to the question is option A: "excess of cleavage," as this is where the sperm enters and initiates the cleavage process.

### Final Answer:
The point of sperm entry forms the "excess of cleavage." Therefore, the correct option is **A: excess of cleavage**.

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