Fig 1. Smad4 signaling is required for germ cell survival.

(A) Scheme of germ-cell-specific knockout strategy. Tamoxifen was injected at E9.5 and E10.5, and ovaries were recovered at indicated stages. (B) Representative image of E17.5 Smad4 (Stella) mutant and control ovarian tissue sections stained for MVH and DAPI. (C,D) Temporal changes of germ cell number (C) and cleaved-caspase3 positive germ cells (D) in control and Smad4 (Stella) mutant ovaries. Sample numbers used for counting were indicated in S1 Data. Significance was assessed using one-way ANOVA followed by Tukey’s post-hoc tests for selected pairs of genotypes. Scale bars: 50 μm. We used Smad^flox/flox, Smad4^flox/+, and Smad4^flox/+ StellaMerCreMer ovaries as the control.