Fig. 2

GSK-3β was indispensable for oocyte survival in fetal mice. a, b Inhibition of GSK-3β by BIO led to dramatic oocyte loss in fetal ovaries. Before the examination, ovaries at 14.5 dpc were cultured in vitro with either DMSO (as the control) or the GSK-3β-specific inhibitor BIO for 4 days. a Oocytes were stained with DDX4 (green). The nucleus was stained with Hoechst (blue). b Statistical analysis showed that the total number of oocytes decreased time-dependently following BIO treatment for 2, 3, and 4 days (Additional file 8: Individual data values). The data are presented as means ± s.d. Different letters (a–c) denote a statistically significant difference between the groups (ANOVA and Holm-Sidak test). c, d Inhibition of GSK-3β caused severe cellular apoptosis in the fetal ovaries. Before the examination, ovaries at 14.5 dpc were cultured in vitro with DMSO or BIO for 3 days. c Active Caspase-3 signals (green) corresponded to apoptotic cells. Oocytes were stained with DDX4 (red). The nucleus was stained by Hoechst (blue). d Statistical analysis showed that the number of apoptotic oocytes per section increased significantly following BIO treatment (Additional file 8: Individual data values). The data are presented as mean ± s.d. The asterisk (*) denotes a statistically significant difference between the control and treatment groups. *P < 0.05, **P < 0.01, and ***P < 0.001 (t test). Scale bars, 200 μm