Which statement is incorrect ?

Options

A. Mast cells and basophils secrete histamine and heparin
B. Mast cells are long lived, basophils are short lived
C. Mast cells are smaller than basophils with a bilobed nucleus
D. Mast cells are relatively sessile, basophils are mobile

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks to identify which statement about mast cells and basophils is incorrect.

2. **Identifying Characteristics of Mast Cells and Basophils**:
- Both mast cells and basophils are involved in the early phase of immediate hypersensitivity reactions.
- They are both granulated cells that contain histamine and heparin.

3. **Evaluating the Statements**:
- **Statement 1**: "Mast cells and basophils secrete histamine and heparin."
- This statement is correct as both cell types do secrete these substances.

- **Statement 2**: "Mast cells are long-lived; basophils are short-lived."
- This statement is also correct. Mast cells have a longer lifespan compared to basophils.

- **Statement 3**: "Mast cells are fixed in the tissues; basophils circulate in the blood."
- This statement is correct as mast cells are indeed found in tissues while basophils circulate in the bloodstream.

- **Statement 4**: "Mast cells are smaller than basophils with a bilobed nucleus."
- This statement is incorrect. Mast cells are generally larger than basophils and have a round nucleus, not bilobed.

4. **Conclusion**: The incorrect statement is that mast cells are smaller than basophils with a bilobed nucleus. The correct answer is option 4.