Hemal nodes are characterized by the presence of large numbers of erythrocytes. Lymph nodes (see below) and hemal nodes share some similarities of structure, but really are fundamentally different organs both qualitatively and quantitatively. Both lymph and hemal nodes contain diffuse lymphatic tissue, and in most cases have nodular tissue in the form of germinal centers, as well. Like the lymph node, the hemal node has a cortex and a medulla, and germinal centers are frequently seen. There's a distinct capsule, and hemal nodes are served at the hilus by an afferent arteriole. [http://www.vetmed.vt.edu/education/curriculum/vm8054/labs/lab13/lab13.htm]

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