In a lymph node, which zones predominantly contain B cells and which contain T cells?

In a lymph node, which zones predominantly contain B cells and which contain T cells?

• A. Cortex contains T cells; Paracortex contains B cells; Medullary cords contain plasma cells and macrophages.
• B. Cortex contains B cells; Paracortex contains T cells; Medullary cords contain plasma cells and macrophages.
• C. Cortex contains B cells; Paracortex contains plasma cells; Medullary cords contain T cells.
• D. Cortex contains plasma cells; Paracortex contains macrophages; Medullary cords contain B cells.

Answer: (B)

Lymph node organization reflects which lymphocytes are most active in each region. B cells are concentrated in the cortex, especially in the lymphoid follicles that may develop germinal centers when B cells are activated. T cells reside mainly in the paracortex, the zone just beneath the cortex, where they interact with antigen-presenting cells and pass through high endothelial venules to enter the node. The medullary cords in the medulla contain plasma cells (differentiated B cells) and macrophages, forming part of the efferent side of the node’s immune filtering. So, the cortex is rich in B cells, the paracortex houses T cells, and the medullary cords contain plasma cells and macrophages.

Lymph node organization reflects which lymphocytes are most active in each region. B cells are concentrated in the cortex, especially in the lymphoid follicles that may develop germinal centers when B cells are activated. T cells reside mainly in the paracortex, the zone just beneath the cortex, where they interact with antigen-presenting cells and pass through high endothelial venules to enter the node. The medullary cords in the medulla contain plasma cells (differentiated B cells) and macrophages, forming part of the efferent side of the node’s immune filtering.

So, the cortex is rich in B cells, the paracortex houses T cells, and the medullary cords contain plasma cells and macrophages.