Figure 4

Doxycycline induction time length affects the severity of trachea phenotype in the Sox9 knockout lungs. (A) Time-plugged female mice were fed with doxycycline for different time periods, and lungs were collected at embryonic day (E) 18.5. (B-G) Doxycycline induction from (B, C) E7.5 to E13.5, (D, E) E7.5 to E12.5, and (F, G) E7.5 to E11.5. (C, E, G) The severity of the phenotype in the transgenic embryos was inversely correlated with the time length of induction. (B, D, F) No changes were observed in the wild-type lung tracheas. (H-J) E14.5 staged pregnant females were fed with doxycycline. Embryos were harvested at E18.5, and the tissues fixed and stained with Alcian blue to show the cartilage rings. (D) Normal cartilage rings developed in the trachea of the Sox9^Δ/Δ embryos.