Where do B cells mature?

• A. In the liver
• B. In the lymphatic system
• C. In the bone marrow
• D. In the spleen

Answer: (C)

B cells mature in the bone marrow. This primary lymphoid organ provides the environment where B cell precursors rearrange their immunoglobulin genes, form a functional B cell receptor, and undergo selection to minimize self-reactivity, exiting as mature naive B cells. After maturation, they travel to peripheral sites like the spleen and lymph nodes to participate in immune responses. The liver’s role in hematopoiesis is fetal, not for ongoing B cell maturation in adults, while activation and antibody production occur in secondary lymphoid tissues rather than at the maturation site.