In a lymph node, which cell type is primarily located in the medullary region?

In a lymph node, which cell type is primarily located in the medullary region?

• A. B lymphocytes
• B. Macrophages
• C. T lymphocytes
• D. Dendritic cells

Answer: (B)

The medullary region of a lymph node is defined by medullary cords and medullary sinuses. The medullary sinuses are lined with macrophages that actively filter the lymph as it passes through the node, phagocytosing debris and pathogens before the lymph exits via efferent vessels. While medullary cords contain B lymphocytes and plasma cells, and the cortex/paracortex harbor T cells and B cells in follicles, the hallmark cell type of the medulla is the macrophage population in the sinuses. Dendritic cells are more characteristic of antigen presentation in the cortex and paracortex.

The medullary region of a lymph node is defined by medullary cords and medullary sinuses. The medullary sinuses are lined with macrophages that actively filter the lymph as it passes through the node, phagocytosing debris and pathogens before the lymph exits via efferent vessels. While medullary cords contain B lymphocytes and plasma cells, and the cortex/paracortex harbor T cells and B cells in follicles, the hallmark cell type of the medulla is the macrophage population in the sinuses. Dendritic cells are more characteristic of antigen presentation in the cortex and paracortex.