Which of the given option is incorrect about spleen ?

Options

A. It is the graveyard of erythrocytes .
B. It receives only oxygenated blood.
C. It helps in filteration of blood.
D. It is primary lymphoid organ.

Answer

To determine which option is incorrect about the spleen, let's analyze each statement provided in the question step by step.

### Step 1: Analyze the first option
- **Statement**: "It is the graveyard of erythrocytes."
- **Explanation**: This statement is correct. The spleen is known as the "graveyard" for red blood cells (erythrocytes) because it is responsible for the destruction of old and damaged RBCs.

### Step 2: Analyze the second option
- **Statement**: "It receives only oxygenated blood."
- **Explanation**: This statement is incorrect. The spleen receives blood from the splenic artery, which carries oxygenated blood, but it also receives deoxygenated blood through the venous system as it filters blood. Therefore, this statement is misleading.

### Step 3: Analyze the third option
- **Statement**: "It helps in the filtration of blood."
- **Explanation**: This statement is correct. The spleen plays a crucial role in filtering blood, removing old and damaged erythrocytes, and recycling iron.

### Step 4: Analyze the fourth option
- **Statement**: "It is a primary lymphoid organ."
- **Explanation**: This statement is incorrect. The spleen is classified as a secondary lymphoid organ, not a primary lymphoid organ. Primary lymphoid organs are where lymphocytes are produced (like the bone marrow and thymus), while secondary lymphoid organs (like the spleen and lymph nodes) are where immune responses are initiated.

### Conclusion
Based on the analysis, the incorrect statement about the spleen is:
- **Option 4**: "It is a primary lymphoid organ."