Micronucleus test with ethyl methanesulfonate administered by intraperitoneal injection and oral gavage

The effect of route of administration on the outcome of the micronucleus test was studied by administering ethyl methanesulfonate (EMS) by oral gavage (p.o.) and intraperitoneal injection (i.p.) to males of 2 mouse strains, MS/Ae and CD-1. Based on preliminary studies, consisting of a small-scale acute toxicity test and a pilot experiment to determine the optimal sampling time and the appropriate dosages, a micronucleus test was conducted with a 24-h sampling time and doses of 50-400 mg/kg i.p. and p.o. EMS significantly induced micronucleated polychromatic erythrocytes (MNPCEs) with a clear positive dose response by both routes in both strains. Moreover, both routes showed almost the same induction rate of MNPCEs at each dose level tested in both strains.