FIGURE 1.

Deletion of Hox5 function at adult stages leads to distal lung airway expansion. H&E sections through 10-week-old wild-type animals (A,A’), Hox5a^fa^fbbcc mutants (no Cre) (B,B’) and Hoxa5^LoxP/LoxP; Hoxb5^{– /–}; Hoxc5^{– /–}; Tbx4rtTA; TetOCre + mutants (Hox5a^fa^fbbcc; Cre +, C,C’), treated with Doxycycline from 8 to 10 weeks of age. Measured mean alveolar chord length (MACL) values (D). Hox5a^fa^fbbcc double mutant animals (Hoxa5 floxed alleles with no Cre) exhibit enlarged, simplified alveoli with a ∼20% increase in alveolar chord length compared to control lungs. The distal airway expansion phenotype with adult, conditional Hox5 triple mutants increases by ∼45% compared to control lungs. Each shape represents an individual animal. Control, Hox5AABBCC. Scale bars: 50 μm (C); 25 μm (C’). P-values and statistical significance (****P < 0.0001) were determined by an unpaired Student’s t-test.