ABSTRACT Objective: To study the effect of 4selenocarrageenan (Secarra) on leukopenia induced by cyclophosphamide (CTX) in mice. Methods: Semisolid culture of bone marrow colonyforming unitgranulocyte and monocyte (CFUGM) for assessing hematopoietic progenitors of granulocytes and macrophages; Colony forming unitspleen (CFUS) for hematopoietic stem cells; MTT assay for the proliferation of bone marrow cells; Spleen weighing for extramedullary hematopoiesis. Results: Secarra 10~40 mg·kg-1 p....