Figure 4

Analyses of cell proliferation, cell division and cell death. Cell proliferation (PCNA: panels A, B, E and F; BrdU: panels C, D, G and H), cell division (pHH3: panels K, L, O and P) and cell death (TUNEL: panels M and N) were analyzed by immunostaining on lung sections at early and late gestational stages. Both PCNA and BrdU labeled cells in both epithelial and mesenchymal regions were comparable at early stages (E14.5 for PCNA and E13.5 for BrdU) between wild-type (+/+) and knockout (-/-) lungs. Positively stained cells in distal lungs at late stage (E20.5 for PCNA and E18.5 for BrdU) from knockout lungs were markedly reduced, compared with wild-type. PCNA labeling of cardiac muscle was also attenuated in knockout embryos at E20.5 (cf. panels I and J). No apparent differences in TUNEL immunostaining were observed in lung sections at E18.5 between wild-type and knockout. The pHH3 immunostaining was comparable between wild-type and knockout lungs at E14.5, and the lungs from wild-type at E20.5 showed a high index of positive cells, whereas lungs from knockout showed a apparent reduced staining pattern. Note the dividing cells are mainly epithelial. Original magnification: A-D and G-N are 20X; E, F, O and P are 40X.