Additional file 5: Figure S2. Effect of GH on the fertilization ability of aged oocytes. Representative images of sperm binding to the zona pellucida of young, aged, and GH + aged oocytes. Scale bar, 20 μm. Number of sperm binding to the surface of the zona pellucida surrounding young, agedand GH + agedoocytes. Data are means ± SEM of at least three independent experiments. **p < 0.01.