Book 4 - Self Instructional Manual for Cancer Registrars - SEER ...

LymphNodesLymph nodes are oval or bean-shaped masses of lymphoid tissue, densely packed with lymphocytes.They vary in size from a pinhead to a lima bean. They are each covered by a capsule of fibrousconnective tissue. The lymph moves through the afferent (towards the node) lymphatic vessels intothe node where it is filtered through sinus channels lined with reticuloendothelial cel!s I (orhistioeytes) and emerges by an efferent (away from the node) vessel (see Figure 9A for the internalstructure of a lymph node, and Figure 9B for the external view).Figures 9A and 9B. STRUCTURE OF A LYMPH NODELymphaticKf£orentweaselslreticuloendothelial cells (or histiocytes)--Special cells which ingest and destroy old erythrocytesand foreign substances; found mainly in the lymph nodes, liver, spleen, and bone marrow.61