qRT-PCR for Lin28a and Lin28b mRNA in tissues from prepubertal 15, 20, 25, 30 day old and postpubertal (35–45 days old) C57BL/6 female mice, normalized to β-actin in hypothalamus (A), pituitary (B), and ovary (C). Average age of vaginal opening in the mouse colony is indicated by the arrow (31.5 ± 2.4 days). Values are displayed as means ± SEM (n=5–21 mice for each time point). For Lin28a in hypothalamic tissue, *=p<0.05, and **=p<0.01, when compared to 20-day-old tissue. For Lin28a in pituitary tissue, *=p<0.05, when compared to 20-day-old tissue. For Lin28a in ovarian tissue, †=p<0.001, and ‡=p<0.001, when compared to 15 and 20-day-old tissue, respectively. For Lin28b in ovarian tissue, *=p<0.05, **=p<0.01, and ***=p<0.001, when compared to 20 day old tissue.