In the malarial parasite, oocyst is formed in the :

Options

A. erythrocytes of man
B. liver cells of man
C. stomach wall of the female mosquito
D. blood of the female mosquito

Explanation

To determine where the oocyst is formed in the malarial parasite, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Life Cycle of the Malarial Parasite**:
- The malarial parasite, specifically Plasmodium, has a complex life cycle that involves both humans and female Anopheles mosquitoes.

2. **Identify the Initial Infection**:
- When a female Anopheles mosquito bites a human, it injects sporozoites (the infective form of the parasite) into the human's bloodstream.

3. **Sporozoite Development in Humans**:
- The sporozoites travel to the liver cells of the human host, where they undergo asexual reproduction.

4. **Release of Merozoites**:
- After a period of development, the liver cells rupture, releasing merozoites into the bloodstream, where they infect red blood cells and continue to multiply.

5. **Formation of Gametocytes**:
- Some of these merozoites develop into gametocytes (the sexual form of the parasite) within the red blood cells.

6. **Transmission Back to Mosquito**:
- When another mosquito bites the infected human, it ingests these gametocytes along with the blood.

7. **Gametocyte Fusion in the Mosquito**:
- Inside the mosquito's stomach wall, the gametocytes fuse to form zygotes.

8. **Formation of Oocysts**:
- These zygotes then develop into oocysts in the stomach wall of the mosquito.

9. **Conclusion**:
- Therefore, the oocyst is formed in the stomach wall of the female mosquito.

### Final Answer:
The oocyst in the malarial parasite is formed in the **stomach wall of the female mosquito**.