Final answer:
The paracortical area of the lymph node contains white blood cells, specifically T lymphocytes, which are crucial for the body's adaptive immune response.
Step-by-step explanation:
The paracortical area of the lymph node is significant in the function of the immune system. This region primarily contains white blood cells, especially T lymphocytes, which play a crucial role in the adaptive immune response. The lymph node structure is organized such that lymph enters through the afferent lymphatic vessels, passes through the subcapsular sinus (which houses dendritic cells and macrophages), encounters the B cells in the germinal centres within the cortex, and then flows to the paracortical area where T cells are located before exiting the node through the efferent lymphatic vessels.