A direct comparison of mouse and rat bone marrow and blood as target tissues in the micronucleus assay.

Rats and mice were treated concurrently with mitomycin C at a dose of 1 mg/kg/day i.p. for 3 days, a regimen known to induce micronuclei in polychromatic erythrocytes (MN-PCE) in the bone marrow of rats and mice and the peripheral blood of mice. The incidence of micronuclei was evaluated in the peripheral blood and the bone marrow of both species. Early reports suggested that the efficiency of the rat spleen in removing micronuclei from the circulation precluded the use of rat peripheral blood in the detection of chemically-induced micronuclei. The data in the present study demonstrate that the induction of micronuclei in polychromatic erythrocytes as the result of treatment with a clastogen can be demonstrated equally well in the bone marrow or the peripheral blood of both rats and mice.