Fig. 2. Defects in lung epithelial differentiation in G6-Nkx DH embryos. (A-P) G6-Nkx DH lungs exhibit defects in airway development and differentiation. (A,D,G,J) Hematoxylin and Eosin (H+E) staining of lung sections. Notice the increased mesenchymal thickness and reduced sacculation in G6-Nkx DH lungs (J). Wild-type (A) and single heterozygous (D,G) lungs appear normal. SP-C protein expression is more focal in G6-Nkx DH lungs (B,E,H,K). Both aquaporin-5 and SP-C are expressed in a tight, focal pattern that is less evenly distributed throughout the distal alveolar airspaces in G6-Nkx DH lungs compared with wild-type lungs (M-P, arrowheads). CC10 protein expression is reduced in G6-Nkx DH lungs compared with wild-type or single heterozygous lungs (C,F,I,L, arrowheads). Data are from either the left lung or the cranial lobe of the right lung. All histological data are representative of at least five embryos of each genotype. (Q) Microscopic measurements were made to determine the mesenchymal thickness in G6-Nkx DH lungs, as described in the Materials and methods section. These data show a significant thickening in the inter-alveolar mesenchyme of G6-Nkx DH lungs at E18.5. P values ^*<0.001 versus wild-type, Gata6^+/- or Nkx2.1^+/- lungs. Scale bars: 500 µm in C,F,I,L; and 100 µm in A,B,D,E,G,H,J,K,M-P.