Which of the following types of leucocytes is characterized by the presence of the S - shaped nucleus?

Options

A. Eosinophil
B. Basophil
C. Neutrophil
D. Monocyte

Answer

To solve the question regarding which type of leucocyte is characterized by the presence of an S-shaped nucleus, we will analyze each option provided.

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks for the type of leucocyte (white blood cell) that has an S-shaped nucleus.

2. **Reviewing the Options**:
- **Eosinophil**: Eosinophils are known to have a nucleus that is typically shaped like a kidney or a bilobed structure. Therefore, this option is incorrect.
- **Basophil**: Basophils have a nucleus that can be described as having a peanut or a fat shape, which does not resemble an S-shape. Thus, this option is also incorrect.
- **Neutrophil**: Neutrophils are characterized by a nucleus that is divided into multiple lobes (2 to 5), which does not fit the S-shaped description. Hence, this option is incorrect.
- **Monocyte**: Monocytes have a nucleus that is often described as bean-shaped or kidney-shaped. This does not match the S-shaped criteria, making this option incorrect as well.

3. **Conclusion**: After analyzing all the options, it appears that none of the provided leucocyte types have an S-shaped nucleus. However, the closest resemblance to an S-shape is often attributed to basophils, which can have irregular shapes.

4. **Final Answer**: The correct answer to the question, based on the provided options, is **Basophil**.