AN AUTOMATED NEW TECHNIQUE FOR SCORING THE RODENT MICRONUCLEUS ASSAY - COMPUTERIZED IMAGE-ANALYSIS OF ACRIDINE-ORANGE SUPRAVITALLY STAINED PERIPHERAL-BLOOD CELLS

We developed an automated image analysis system to obtain objective da ta for the rodent peripheral blood micronucleus assay with acridine or ange (AO) supravital staining. The system was able to identify micronu cleated reticulocytes (MNRETs) and to evaluate inhibition of bone marr ow cell proliferation by measuring the reticular area of reticulocytes (RETs). We also developed automated equipment to produce homogeneous acridine orange-coated glass slides. This study was designed to compar e automated scoring with manual scoring using 4 model clastogens and 2 mouse strains. The MNRET incidence induced by each clastogen was simi lar for automated and manual scoring, and there was good correlation ( r = 0.92) between the methods. In addition, an index of bone marrow to xicity based on the reticular area of RETs was compared to the convent ional index (% of polychromatic erythrocytes (PCE) to total erythrocyt es; PCE ratio) and was similar. The results indicated that our techniq ue for computer-assisted image analysis for the micronucleus assay wit h AO supravitally stained peripheral blood RETs was comparable to conv entional microscopic scoring, and it was superior in objectivity and s tatistical power. (C) 1998 Elsevier Science B.V. All rights reserved.