Exam 3 Review:  Chapter 21:  Lymph Nodes

cortex - The outer layer of an internal organ or body structure, e.g., the cerebrum, kidney, adrenal gland, or lymph node; the cortex of a lymph node contains many lymph follicles (dendritic cells surrounding germinal centers) which are separated by connective tissue trabeculae and the cortex contains a branching system of channels which route lymph from the afferent lymphatic vessels to the medulla; antigen-presenting macrophages and T and B lymphocytes in the cortex are involved in immune reactions to specific antigens.

medulla - The inner core of an internal organ or body structure, e.g., the cerebrum, kidney, adrenal gland, or lymph node; the medulla of a lymph node contains medullary cords (thin inward extensions of cortical lymphoid tissue) and lymph sinuses spanned by crisscrossing reticular fibers which act as a filter for the passage of lymph from the cortex to the efferent lymphatic vessels which carry lymph away from the lymph node at the hilus; the medulla also contains many macrophages.

germinal center - The light-staining interior of a lymph follicle which contains antigen-presenting macrophages and T and B lymphocytes involved in immune reactions to specific antigens.

medullary cord - A thin inward extension of cortical lymphoid tissue (T and B lymphocytes) which is bounded by lymph sinuses in the inner core (medulla) of a lymph node.

afferent lymphatic vessel - Any of the delicate thin-walled vascular tubes with valves which transport lymph (interstitial fluid = intercellular fluid = tissue fluid) from the tissue spaces into the interior of the cortex of a lymph node by passing the fluid through an opening in the capsule.

efferent lymphatic vessel - Any of the delicate thin-walled vascular tubes with valves which transport lymph (interstitial fluid = intercellular fluid = tissue fluid) from the interior (medulla) of a lymph node by exiting through an opening in the hilus and on through the lymphatic circulation.

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