Fig. 1

FGF and MEK1/2 inhibition disrupts foetal testis development but only MEK1/2 inhibition disrupts germ cell mitotic arrest. A Bright-field and GFP images of E12.5 XY gonad-mesonephros tissue cultured for 72 h with DMSO, or 500 nM of FGFRi, MEKi, p38i or PI3Ki. Scale bar: 100 μm. Dotted lines highlight the gonad. B–E Flow cytometric analysis of Sertoli (B,D) or germ (C,E) cell proliferation based on EdU incorporation in XY E12.5 gonad-mesonephros tissue cultured for 72 h with DMSO, 500 nM of FGFRi, MEKi, PI3Ki or p38i (B,C) or 125, 250, 500 or 1000 nM of FGFRi or MEKi (D,E). F,G Flow cytometric analysis of Sertoli (F) or germ (G) cell proliferation based on EdU incorporation in XY E13.5 gonad-mesonephros tissue cultured for 48 h with DMSO or 500 nM of FGFRi or MEKi. H Immunofluorescent images of E12.5 gonad-mesonephros tissue cultured for 24 h with DMSO, 500 nM of FGFRi or MEKi demonstrating MEK1/2 signalling activity. Top panel: DAPI (blue), MVH (green), NR2F2 (red), pERK1/2 (cyan). Bottom panel: pERK1/2 (grey). Scalebar represents 50 μm. Replicates: A–C n = 6–9, D,E n = 3–16, F,G n = 3, H n = 3–4. Statistics: B, D, E Ordinary one-way ANOVA with Tukey’s multiple comparison, C Brown-Forsythe and Welch ANOVA with Dunnett’s T3 multiple comparisons, F,G Unpaired two-tailed t-test. Error bars: Mean ± SEM. Significance between control and treatment: *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001