Microscopic Components of a Lymph Node

Description

Cortical and medullary compartments are presented in section, with a dense outer cortex surrounding a looser central medulla. Lymphoid follicles occupy the superficial cortex, while the deeper paracortex lies medial to them and leads inward to the medullary cords separated by medullary sinuses. Afferent lymphatic vessels enter the convex surface and deliver lymph into the subcapsular sinus, which communicates with trabecular (cortical) sinuses; an efferent lymphatic exits at the hilum adjacent to the medulla. That architecture matters because it maps directly to lymph flow and antigen handling: particulate antigen and metastatic cells arrive via afferent lymphatics, traverse the sinus system, and encounter macrophages and dendritic cells before lymph leaves through the efferent channel. Follicular hyperplasia with prominent germinal centers points toward reactive patterns, while diffuse effacement of cortex and paracortex raises concern for lymphoma. Sentinel lymph node biopsy in breast cancer and melanoma relies on this same afferent to sinus to efferent pathway, and pathologists often correlate subcapsular sinus involvement with early metastatic spread. Use this artwork in histology and immunology teaching to orient learners to cortex versus medulla and to explain how afferent and efferent lymphatics relate to the sinus network. It also fits surgical oncology texts, pathology atlases, and patient education materials that discuss nodal staging, reactive lymphadenopathy, and routes of metastasis. Anatomical accuracy verified by SciePro's Medical Advisory Board.