Blastula of frog is:

Options

A. Stereoblastula
B. Coeloblastula
C. Discoblastula
D. Superficial blastula

Answer

### Step-by-Step Solution:

1. **Understanding the Blastula Stage**:
- The blastula is an early stage of embryonic development that occurs after the cleavage stage. It typically consists of a hollow ball of cells.

2. **Cell Division in Blastula**:
- In frogs, the blastula stage usually consists of 8 to 16 cells. During this stage, the cells continue to divide and form a cavity.

3. **Formation of Blastocoel**:
- As the cells divide, a fluid-filled cavity known as the blastocoel is formed inside the blastula. This cavity is crucial for the further development of the embryo.

4. **Types of Blastula**:
- There are different types of blastulae based on the presence or absence of a blastocoel:
- **Stereoblastula**: No blastocoel is present; the entire space is filled with cells. This type is found in certain invertebrates like annelids and mollusks.
- **Coeloblastula**: This is the type found in frogs. It has a hollow structure with a blastocoel present.
- **Discoblastula**: Characterized by a disc-shaped blastula, typically found in fish, where cleavage is meroblastic due to the presence of yolk.
- **Superficial Blastula**: Found in crabs, where the inner cell mass is on the sides and small cavities are scattered in the middle.

5. **Conclusion**:
- Based on the characteristics of the blastula in frogs, the correct answer is that the blastula of the frog is a **coeloblastula**.

### Final Answer:
The blastula of the frog is a **coeloblastula**.

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