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. 2006 Oct 26;25(22):5383–5395. doi: 10.1038/sj.emboj.7601398

Figure 4.

Figure 4

The timing of Six3 deletion is crucial for the lens phenotype. Ubiquitous, early deletion of Six3 via tamoxifen injection of pregnant Six3f/Δ;CAGG-Cre-ER dams at E7.8 and E8.5 (A′–F′) and late deletion via injection at E9.5 and E10.0 (G′–I′) were performed. Mutant embryos were analyzed at E10.5. Only early deletion of Six3 caused a failure in lens specification. (A′) Six3 expression was not detected in the PLE (arrow) or optic vesicle (arrowhead). (A′, B′) The PLE did not thicken and the lens placode did not form. (C′, D′) Defective lens induction and specification was confirmed by the absence of Pax6 and Sox2 from the PLE of the mutant embryos (arrows). (E′) Expression of Meis1 remained in the SE. Although Six3 was deleted ubiquitously and the shape of the optic vesicle was abnormal, neural retina expression of Pax6 (arrowhead in C′), and Chx10 (arrow in F′) remained. (G′–I′) Embryos subjected to late Six3 deletion exhibited normal or slightly small lens pits. Pax6 expression was not affected (arrow in H′), and Sox2 was either not affected or was slightly reduced (I′). (J) Graphic representation of the number of analyzed mutant embryos with early or late Six3 deletion per the observed lens phenotype (normal, small, or no lens pit (LP)).