Mitotic index and lymphocyte proliferation kinetics in testing the genotoxicity of chemical agents.

The mitotic (MI) and proliferation (PI) indices were investigated to determine the effect of N-nitrosodimethylamine (NDMA) in cultured blood lymphocytes of cows, pigs, and sheep. Our results confirmed the ability of all animal lymphocytes to metabolize this chemical agent to mutagenic products. Treatment with NDMA caused inhibition of MI and PI which were more expressive in bovine lymphocytes. In addition, statistically significant heterogeneity of the first, second, and third metaphases between the treated and untreated cultures was found. Mean PI values were used to estimate cellcycle delays showing the highest effect in bovine lymphocytes.