The point of sperm entry during fertilization forms

Options

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

Explanation

To answer the question regarding what the point of sperm entry during fertilization forms, we can break down the solution into the following steps:

### Step-by-Step Solution:

1. **Understanding Fertilization**:
- During fertilization, a sperm cell penetrates the ovum (egg cell). This event is crucial for the initiation of embryonic development.

2. **Identifying the Point of Sperm Entry**:
- The point where the sperm enters the egg is significant as it establishes the orientation of the embryo. This point is typically located in the animal hemisphere of the egg.

3. **Dorsoventral Axis Formation**:
- The entry of the sperm defines the dorsoventral axis of the embryo. This means that the side where the sperm enters will become the ventral side, while the opposite side will become the dorsal side.

4. **Formation of the Gray Crescent**:
- The gray crescent is a region that forms opposite to the point of sperm entry. It is critical for the development of the embryo and marks the area where important developmental processes begin.

5. **Cleavage and Development**:
- The point of sperm entry also influences the pattern of cleavage (cell division) that follows fertilization. The cleavage is typically more pronounced on the side of the egg where the sperm entered, leading to the formation of the excess of cleavage.

6. **Conclusion**:
- Therefore, the point of sperm entry during fertilization forms the "excess of cleavage" as it influences the embryonic development and the orientation of the embryo.

### Final Answer:
The point of sperm entry during fertilization forms the **excess of cleavage**.

---