The following are found in Taenia solium. Which one is the correct sequence?

Options

A. Onchosphere, hexacanth, cysticercus, matured proglottid, gravid
B. Matured proglottid, cysticercus, gravid, onchosphere, gravid
C. Hexacanth, cysticercus, gravid, oncho-sphere, matured proglottid
D. Gravid, onchosphere, cysticercus, hexacanth, matured proglottid

Answer

To determine the correct sequence of stages in the life cycle of Taenia solium (the pork tapeworm), we can break down the process step by step:

### Step-by-Step Solution:

1. **Identify the First Stage: Oncosphere**
- The life cycle of Taenia solium begins with the oncosphere, which is the larval stage that is ingested by the host (usually a pig).

2. **Second Stage: Hexakanth**
- After the oncosphere is ingested, it develops into the hexakanth larva. This stage is characterized by the presence of hooks.

3. **Third Stage: Cysticerus**
- The hexakanth then transforms into the cysticerus stage. This is the larval form that resides in the tissues of the pig, particularly in the muscles.

4. **Fourth Stage: Mature Proglottid**
- Once the cysticerus is ingested by a human (the definitive host), it develops into a mature proglottid. Proglottids are segments of the tapeworm that contain reproductive organs.

5. **Fifth Stage: Gravid Proglottid**
- The mature proglottid can then develop into a gravid proglottid, which is filled with eggs.

6. **Final Stage: Eggs and Oncosphere**
- The gravid proglottid releases eggs into the environment, which can then be ingested by pigs, leading to the formation of new oncospheres, thus continuing the cycle.

### Correct Sequence:
- Oncosphere → Hexakanth → Cysticerus → Mature Proglottid → Gravid Proglottid → Eggs

### Conclusion:
The correct sequence of stages in the life cycle of Taenia solium is:
1. Oncosphere
2. Hexakanth
3. Cysticerus
4. Mature Proglottid
5. Gravid Proglottid

The answer is **Option A**.

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