Fig. 1.

Oocyte-expressed CDC42 regulates the activation of primordial follicles in neonatal mouse ovaries. a Cellular localization of CDC42 in perinatal ovaries. Ovaries were stained for CDC42 (green) and the oocyte marker DDX4 (red) at the indicated time points. Nuclei were counter-stained by Hoechst (blue). CDC42 mainly localized to the intracellular membrane of the activated oocytes (arrows). b The total protein levels and active form of CDC42 (CDC42-GTP) from 1 to 7 dpp ovaries. Western blot and CDC42-GTP pull-down assays showed that both total and CDC42-GTP expression significantly increased in ovaries at 5 dpp. c CDC42-GTP pull-down assay showed that both ML141 and ZCL278 could significantly suppress the expression of CDC42-GTP in culture. d Ovaries at 2 dpp were cultured in media alone (control) or with CDC42 inhibitor ML141 or ZCL278 for 5 days in vitro. Oocytes were stained with DDX4 (red). Nuclei were dyed with a Hoechst counter-stain (blue). The activation of oocytes was remarkably suppressed in ML141 or ZCL278-treated ovaries, and few activated oocytes were observed in these ovaries compared to the control. e, f Quantification of ovarian follicles in cultured ovaries with different treatments. The number of activated follicles significantly decreased in cultured ovaries after ML141 or ZCL27 treatment, and the total number of oocytes was comparable in cultured and treated ovaries (Additional file 10: Individual data values). The asterisks indicate a significant difference between control and treated ovaries. The experiments were repeated at least three times, and representative images are shown. * P < 0.05, *** P < 0.001. Data are presented as the means ± S.D. Scale bars: (a) 50 μm, (d) 20 μm