Fig. 6.

Pax6 is necessary and sufficient for Shroom3 expression in the lens. (A-C) Shroom3 expression from the lacZ promoter trap allele was assessed in control (A,B) or Pax6^Sey/Sey (C) mouse embryos by X-gal staining. (D-G) Control or Pax6 mRNA-injected Xenopus embryos were assayed for Shroom3 expression by in situ hybridization. Arrowheads indicate ectopic Shroom3 expression. (H) RNA was isolated from animal caps derived from control or Pax6 mRNA-injected Xenopus embryos and analyzed by RT-PCR using primers specific to Xenopus Shroom3 or the housekeeping gene Ef1α. (I-L) Control mouse embryos (I) or those conditionally deficient for Pax6 (Le-Cre; Pax6^flox/flox; AP2α-Cre; Pax6^flox/flox) (J,K) or Sox2 (AP2α-Cre; Sox2^flox/flox) (L) in the surface ectoderm were cryosectioned and labeled for Shroom3. (M-P) Pax6 expression in E10.5 wild-type or conditional mutant mouse lens pits as assessed by immunofluorescence. Hoechst 33258 labeling was used to visualize nuclei. lpl, lens placode; ple, presumptive lens ectoderm; lp, lens pit; pr, presumptive retina.