Identification and dynamics of paraquat in the bone marrow, thymus and spleen in rats using immunohistochemical techniques.

We reported the immunohistochemical identification of paraquat in the immune and hematopoietic systems such as bone marrow, spleen and thymus. Twelve paraquat-poisoned rats were sacrificed in 3 h, 12 h, 3 days, 7 days and 10 days after intravenous administration of paraquat. In the bone marrow, paraquat was localized in several types of blood cells (granulocyte, erythrocyte and megakaryocyte) and their precursors between 24 h and 7 days after the injection. In the thymus, paraquat was mainly localized in the medulla between 12 h and 7 days after the injection, whereas in the spleen, it was mainly localized in the red pulp between 12 h and 10 days after administration of paraquat.