The stage of Entamoeba histolytica that causes intestinal ulceration is

Options

A. Trophozoite
B. Metacystic trophozoite
C. Binucleate stage
D. Tetranucleate stage.

Answer

To determine the stage of *Entamoeba histolytica* that causes intestinal ulceration, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Organism**: *Entamoeba histolytica* is an anaerobic protozoan that can cause intestinal infections in humans. It is important to know its life cycle and the different stages it goes through.

2. **Identify the Stages**: The life cycle of *Entamoeba histolytica* includes several stages:
- Trophozoite stage
- Pre-cystic stage
- Cystic stage

3. **Infection Process**: Humans become infected by ingesting food or water contaminated with cysts of *Entamoeba histolytica*. The cysts are typically in a tetranucleate form.

4. **Cyst Activation**: Once the cysts reach the small intestine, digestive enzymes (like trypsin) break down the cysts, releasing metacystic trophozoites.

5. **Maturation of Trophozoites**: The metacystic trophozoites then mature into trophozoites, which are the active feeding forms of the organism.

6. **Tissue Damage**: The mature trophozoites produce a substance called histolysin, which is responsible for causing tissue damage and ulceration in the intestinal lining.

7. **Conclusion**: Based on this information, the stage of *Entamoeba histolytica* that causes intestinal ulceration is the **trophozoite stage**, specifically the mature trophozoites that produce histolysin.

### Final Answer:
The stage of *Entamoeba histolytica* that causes intestinal ulceration is the **trophozoite stage**.

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