Int. J. Environ. Res. Public Health 2010, 7 3. Results 2038 Mice in the HU treatment group sustained approximately 50% reduction (P < 0.05) in ovarian weight compared with their counterparts in the control group (Figure 2). Interestingly, the reduction in mean ovarian weight among HU treated mice was accompanied by concomitant reductions in serum E2 concentrations (P < 0.05; Figure 3) and ovulation rate (P < 0.05; Figure 4). Figure 2. Mean Ovarian Weight of HU-treated Versus Control Mice. Figure 3. Effect of HU on Serum E2 Concentrations in Female Mice Treated IP with 30 mg HU/kg for 28 days; n = 5 per Group. Results are expressed as mean ± SE (HU = treated mice; Control = vehicle treated mice. Asterisks indicate a significant difference from controls (P < 0.05).