Structural changes in the mouse thymus and lymph node after emetine treatment.

The effect of emetine which is a potent immunosuppresant was studied on the thymus and lymph node. The subcapsular zone of the thymus was depleted and large number of adherent cells accumulated in this thymic region. The medulla enlarged but the cortico-medullary border remained distinct. In the paracortex (T dependent area) of the lymph node many non-lymphoid pyroninophil cells appeared which is followed by an increased cell proliferation 24 hours after emetine injection. 48-60 hours after administration many macrophage-like cells appeared in the medullary sinuses. This macrophage invasion precedes the adherent cell accumulation in the subcapsular zone of the thymus suggesting a possible non-lymphoid (adherent) cell migration from the lymph node's paracortex to the thymus.