(A) Cell-cycle analysis of cortical progenitors treated with ethanol for 4 days. (A i-iii) Flow-cytometric frequency histograms of progenitors stained with propidium iodide (PI) for DNA content. (A ii,iii) Ethanol stimulates DNA synthesis and cell-cycle progression, as indicated by the increase in area under the S-phase and G2/M peaks, relative to controls. B i-iii, Quantitative analyses of cell-cycle. (B i,ii) Ethanol significantly increased the number of cells entering S and G2/M-phases of the cell-cycle. (B iii) The G2/S ratio was unchanged at low ethanol doses, but significantly increased with the high dose. (B iv) Ethanol did not induce apoptosis at either dose used, and very little DNA fragmentation was observed in the sub-G0/1 range in (Ai-iii). Asterisks indicate statistical-significance, p < 0.05.