The precursor of tissue macrophages are

Options

A. Lymphocytes
B. Eosinophils
C. Monocytes
D. None of these

Answer

To solve the question "The precursor of tissue macrophages are," we need to analyze the provided options and understand the role of each type of cell mentioned.

### Step-by-Step Solution:

1. **Understanding the Options**:
- **Lymphocytes**: These are a type of white blood cell involved in the immune response. They are not the precursors of macrophages.
- **Eosinophils**: These are also a type of white blood cell that primarily deals with parasitic infections and allergic reactions. They do not give rise to macrophages.
- **Monocytes**: These are a type of white blood cell that is produced in the bone marrow. They circulate in the bloodstream and can differentiate into macrophages when they migrate into tissues.
- **None of these**: This option suggests that none of the previous options are correct.

2. **Identifying the Correct Precursor**:
- Among the options, monocytes are known to be the precursors of tissue macrophages. When monocytes leave the bloodstream and enter tissues, they differentiate into macrophages.

3. **Conclusion**:
- The correct answer to the question is **monocytes**, as they are the direct precursors to tissue macrophages.

### Final Answer:
**Monocytes**