Figure 4. Characterization of E2F3a/E2F5 double transgenic eyes at E15.5. A, B: Expression of E2F3a and E2F5 transgenes was confirmed by in situ hybridizations with E2F3a and E2F5 riboprobes. Hybridization signals were captured as dark-field images. The E2F3a (A) and E2F5 (B) transgenes were specifically expressed in lens fiber cells, as described previously [15]. C: Ocular histology of the E2F3a/E2F5 double transgenic lenses showed modest alterations in fiber cell elongation and the presence of extra nuclei in the center of the lens. D: The same percentage of fiber cells were BrdU positive in the double transgenic lens as in the E2F3a single transgenic lens described previously (Table 1) [15]. Scale bars=500 μm.