Fig. 8. Histology of lung tissue from 1III4-deficient embryos. Representative sections of the lungs of mutant (B,D,F,H) and control (A,C,E,G) embryos through comparable regions are shown. Note the smaller and more compact size of the mutant lung (B) compared with controls (A) at 18.5 dpc. At higher magnification, it is apparent that the alveoli (asterisk) in 1III4-deficient embryos (D) are only poorly developed with marked mesenchymal thickening around the terminal air spaces compared with wild type (C). At 13.5 dpc, no apparent differences in lung development are visible in mutant (F) when compared with wild-type (E) embryos. Staining for surfactant protein C demonstrates that differentiation of airway epithelial precursor cells is not defective (G,H). Br, Bronchiole; H, heart; L, lung. Scale bars: 1 mm in A,B; 250 µm in C,D; 100 µm in E,F; 50 µm in G,H.