Impact of ZDV and NVP on the mitotic index of Allium cepa root cellsa exposed for 48 hr.

aEach experimental group contained 10 bulbs and 2–3 root tips from each bulb were squashed together on one slide. On each slide 40–100 cells were examined. Values shown are means ± standard deviation of the mean.bEC50 is the concentration of drug that inhibits Allium root growth length by 50%; 10% of EC50 is 5% of total root growth length.cFor the percentage of cells in mitosis: for unexposed vs.32.5 µM ZDV, p = 0.02; for ZDV 50% of EC50 vs. NVP 50% of EC50, p = 0.03. All other associations were statistically non-significant.