Fig. 5. Phosphorylation of Smad1 protein in the developing eyes. Nuclei were visualized by blue labeling with DAPI (A,C,E,G,I,K,M,O). Phosphorylated Smad1 (pSmad1) was detected by immunohistochemistry (green fluorescence) (B,D,F,H,J,L,N,P). At E12, pSmad1 was detected in the cytoplasm and the nucleus of most of the cells in wild-type (B) and transgenic eyes (D). At E15, pSmad1 levels decreased in corneal stroma cells in both wild type (F) and transgenic eyes (H). In transgenic P1 and P7 eyes (L,P), pSmad1 levels were significantly reduced in the lens epithelium, the iris, the ciliary body and the corneal endothelium compared with the wild-type eyes (J,N). However, pSmad1 labeling in the corneal epithelial cells was not significantly affected in transgenic eyes (compare white arrowheads in N and P). Arrowheads in A-H indicate the anterior margin of the optic cup. Arrows in I,J,M,N indicate the infolding ciliary epithelium, which was absent in the transgenic eyes. The asterisk in P indicates nonspecific fluorescent labeling. Abbreviations: L, lens; NR, neural retina. Scale bars: 100 µm.