EFFECTS OF CYTOXAN ON CHROMOSOMES OF MOUSE BONE MARROW

Mice were treated with the bifunctional alkylating agent, cytoxan. Chromosomes of bone marrow were analysed at different time intervals after treatment. Chromatid-type aberrations occured with delayed effect. Aberrations had their maxima at 24 h. After this time, the number of damaged cells decreased continously. Practically no more aberrations were seen 96 h. after treatment. Chromosome-type aberrations were not observed. Damaged cells were eliminated not later than after the first mitosis. There were no metaphases with stable aberrations. It is evident, from the pattern and time of induction of aberrations, that the cell cycle was delayed by cytoxan treatment. Differences from the results of radiation cytogenetics are obviously based on different types of aberration induced by alkylating agents and by ionizing radiation. The genetric risk of cytoxan-treated cells in somatic tissue is discussed. We have evidence that the cytoxan-induced, microscopically visible aberrations in these tissues do not present a significant genetic danger. Probably the point mutations and undetectable small deletions give a much higher genetic risk. © 1969.