Figure 2. Mouse cells have a significantly higher number of micronuclei in comparison with human cells after the same genotoxic damage. WI38 human and HME mouse fibroblasts were treated with 1.5μg/mL neocarzinostatin (NCS) for 2 hours in serum free medium, then cells were washed and fed with regular growth media (10% FBS). Micronuclei were scored after 72 hours. For both species, fibroblasts were both of embryonic or adult origin. The percent of cells containing at least one micronucleus was scored on a minimum of 400 cells, and data are average of 4 and 8 independent experiments for human and mouse, respectively. Significance was calculated with Student's T test (***P<0.001). Non-damaged WI38 and HME cells were included as controls.