Effect of Urethane (Ethyl Carbamate) on the Mitotic Activity in the Bone Marrow of Normal Mice*

By A. Rosix, M.D. F OLLOWING OBSERVATIONS of Haddow and Sext.o& on the ret.arding effect of urethane (ethyl carbamate) on animal tumors, attempts were made to influence the course of leukemia in both human 1)eings and animals vit1i the aid of this drug. Patterson, Haddow et al.2 succeeded in demonstrating a fall in the total w’hite cell count with a return towards a normal differential pattern in cases of myeloid and lymphoid leiikemias in man. Many other aut hors confirmed these results.3 ‘#{176} A similar effect of urethane was revealed in experiments done with the myeloid and lymphoid leukemias of mice.”’5 The mechanism 1)y which urethane leads to a reduction of the number of immature cells in the peripheral blood in leukemia is not. known. Observations on bone marrow of urethane treated! human beings and animals suggest the possiliility that urethane has no arresting effect on the mitotic activity of normal bone marrow3”’ 12 but selectively inhibits the multiplication of leukotic cells.3 ’ t2a, 15 In the present. study the effect of urethane on the mitotic activity of bone marrow cells of normal mice -as investigated.