In mammals the role of spleen is `:-`

Options

A. Graveyard of RBC
B. Reservoir of blood
C. Haemopoletic organ
D. All

Answer

**Step-by-Step Solution:**

1. **Understanding the Spleen's Role**: The spleen is an important organ in mammals that performs multiple functions related to blood and immune system.

2. **RBC Destruction**: One of the primary roles of the spleen is to act as a "graveyard" for red blood cells (RBCs). After their lifespan (approximately 120 days), old and damaged RBCs are filtered out and destroyed in the spleen. This process involves macrophages that engulf and digest these cells.

3. **Blood Filtration**: The spleen also functions as a filter for blood. It removes pathogens and debris from the bloodstream, thus playing a crucial role in maintaining blood quality and immune defense.

4. **Hemopoiesis**: The spleen can also be considered a hemopoietic organ, especially during fetal development, where it contributes to the formation of blood cells (hematopoiesis). In adults, while the bone marrow is the primary site for blood cell production, the spleen can still produce certain types of blood cells in response to specific needs.

5. **Conclusion**: Given these functions, the correct answer to the question is that the spleen acts as a graveyard for RBCs, filters blood, and can function as a hemopoietic organ. Therefore, the comprehensive answer is "all of the above."

**Final Answer**: In mammals, the role of the spleen includes being the graveyard of RBCs, filtering blood, and serving as a hemopoietic organ.

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