Fig. 3.

Foxd1 is necessary for normal lung development. A: newborn Foxd1^−/− mouse (left) shows cyanosis, abdominal distention, an empty stomach, and the mouth wide open, indicating respiratory distress; a littermate control (right) shows normal pink skin color and a stomach full of milk. B: lung weight-to-body weight and kidney weight-to-body weight ratios were significantly reduced in Foxd1^−/− mice (*P < 0.05, ***P < 0.001). C: lung sections stained with hematoxylin and eosin (top and middle) and immunostained for α-SMA (bottom) show normal lung septation and alveolar development in a Foxd1 heterozygous mouse and abnormal thickened interstitial mesenchyme with infrequent septation and markedly reduced airway space in a Foxd1^−/− mouse. Scale bars: 500 μm (top), 50 μm (middle), and, 200 μm (bottom).