Erythropoiesis in human adults occurs in

Options

A. Bone marrow
B. Kidney
C. Liver
D. Spleen

Answer

**Step-by-Step Solution:**

1. **Understanding Erythropoiesis**: Erythropoiesis is the process of producing red blood cells (RBCs) in the body. It is essential for maintaining adequate levels of oxygen in the blood.

2. **Erythropoiesis in Fetal Development**: In human development, erythropoiesis begins in the yolk sac during the early stages of embryonic development. As the fetus grows, the liver takes over this function.

3. **Transition to Adult Erythropoiesis**: After birth (parturition), the primary site of erythropoiesis shifts from the liver to the bone marrow. This is the main site where red blood cells are produced in adults.

4. **Role of Bone Marrow**: The bone marrow is responsible for the continuous production of RBCs throughout an adult's life. It contains stem cells that differentiate into red blood cells.

5. **Other Organs**: While the kidney and spleen are involved in the lifecycle of red blood cells, they do not produce them. Instead, the spleen is known for the destruction of old or damaged RBCs, while the kidneys play a role in filtering blood and regulating erythropoiesis through the secretion of erythropoietin.

6. **Conclusion**: Therefore, the correct answer to the question is that erythropoiesis in human adults occurs in the bone marrow.

**Final Answer**: Erythropoiesis in human adults occurs in the bone marrow.

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