Fig. 4

FGF-2 activates GDNF expression in TECs via FGFR1. a Quantification of GDNF levels by ELISA in conditioned media from TECs isolated from Fgfr1^+/+ or Fgfr1^−/− mice. Bar = 1 cm. b Images of testes from busulfan-treated (45 mg kg⁻¹) WT mice 12 weeks post transplantation with PBS (Φ), Fgfr1^+/+ TECs or Fgfr1^−/− TECs. Testis weights are indicated on the right (n = 4). c H&E images of testis sections from control (Fgfr1^+/+) or endothelial-specific deletion of Fgfr1 (Fgfr1^iΔEC/iΔEC) mice at 12 weeks after tamoxifen treatment to induce fgfr1 deletion from ECs. Red stars indicate empty seminiferous tubule. Bar = 100 μm. d Representative bright-field and GFP images of GFP⁺ SSCs co-cultured with TECs with the addition of FGF ± GDNF at the indicated concentrations after 4 weeks. SSC colony number and size over time are shown on right. e Immunofluorescence images of testis sections from Fgfr1^+/+ or Fgfr1^iΔEC/iΔEC mice 5 weeks after busulfan treatment at the indicated concentrations. Sections were immunostained for GDNF with relative GDNF intensity quantified on the right (n = 3). f Representative images of testis sections immunostained for the SSC markers Lin28 and Sall4 from Fgfr1^+/+ (n = 3) or Fgfr1^iΔEC/iΔEC (n = 4) mice 5 weeks after busulfan treatment (10 mg kg⁻¹). Sall4⁺ or Lin28⁺ cells are quantified on the right. g Representative images of testis sections from WT mice (n = 3–4) treated with busulfan and transplanted with PBS (Φ), Fgfr1^−/− TEC or Fgfr1^+/+ TEC. Sections were stained with H&E and immunostained for Lectin-PNA, DDX4, CD49f and PLZF. Quantification of spermatogenic seminiferous tubules and PLZF⁺ cells are on the right. All data are presented as the mean ± s.e.m. Bar = 50 μm. *P < 0.05, ***P < 0.001. Data shown are representative of two independent experiments. Two-tailed unpaired T-test