Fig. 3.

Mesenchymal Hoxa5 ablation affects SOX9 spatial expression in trachea. (A,B) SOX9 immunostaining showed ectopic mesenchymal SOX9 expression along the secondary bronchi of E14.5 Hoxa5^−/− embryos. Insets show higher magnifications of the boxed areas. Double arrows indicate the SOX9 expression domain along the secondary bronchi. (C-F′) SOX9 expression was detected outside of the cartilage nodules in E18.5 Hoxa5^−/− and Hoxa5^flox/flox; Dermo1^+/Cre mutants (arrows). (G-J) Collagen type II staining was reduced in Hoxa5^−/− and Hoxa5^flox/flox; Dermo1^+/Cre mutants (arrows). (K) qRT-PCR analysis of Hoxa5, Sox9, Sox5, Sox6 and Col2a1 expression levels in E18.5 control and Hoxa5^−/− tracheas. Mean±s.e.m. are shown. *P<0.05, **P<0.01, ***P<0.001 (Student's t-test). Scale bars: 100 µm.