AP BIOLOGY

Detailed explanation-1: -In lymph nodes, most T cells are located in the paracortical area, which in the mouse is found approximately 150–200 mm below the organ’s surface.

Detailed explanation-2: -Adaptive Immunity Naïve T cells enter lymph nodes from the blood via specialized vascular regions called high endothelial venules (HEV). As described above, these cells then browse the dendritic cell networks in the T-cell zone of the lymph node (the paracortex).

Detailed explanation-3: -A simplified drawing of a human lymph node. B cells are primarily clustered in structures called lymphoid follicles, whereas T cells are found mainly in the paracortex.

Detailed explanation-4: -The organ is composed principally of two types of cells, called, respectively, lymphocytes (specifically, T cells, B cells, and natural killer cells) and reticular cells. The reticular cells form a loose meshwork, as in a lymph node, while the spaces between them are packed with lymphocytes.

Detailed explanation-5: -Typically, naïve T lymphocytes gain access from the blood vasculature to LNs through high endothelial venules (HEVs) in the paracortical T cell zone, a location where they are able to survey for antigen prior to exiting the LN via efferent lymphatics.