Figure 5

Sox2- ablated optic cup progenitor cells (OCPCs) exhibit Ctnnb1- independent proliferation defects. BrdU incorporation of cycling cells was quantified in single-mutants, double-mutants and wild-type controls after a single pulse at E14.5, and OCPC proliferation in wild-type controls and Sox2 single-mutants was assessed at 3 developmental time-points. (A) No significant difference in the BrdU/Ki67 index between wild-types and Ctnnb1^{lox(ex2–6)/lox(ex2–6)} single-mutants at E14.5 is detected, but Sox2 single-mutants show significantly reduced BrdU incorporation. There is no significant difference in BrdU incorporation between Sox2 single-mutants and Sox2/Ctnnb1 double-mutants. (B-G) Incorporation of BrdU and concomitant staining for phospho-Histone-H3 between E14.5 and E18.5. Normal ciliary epithelium (CE) development from E14.5-E18.5 is characterized by a gradual reduction in BrdU incorporation over time (B-D, white brackets in C and D). In Sox2 single-mutants, the peripheral BrdU-negative region expands over time (E-G, white brackets in F and G). (H-J) Ki67 is maintained in the peripheral optic cup (OC) of controls at E14.5 (G) but is increasingly reduced at E16.5 (H) and E18.5 (I). (K-M) Ki67 expression in the peripheral OC of Sox2-mutants is similar to that of controls at E14.5 (J) but is increasingly reduced in the periphery at E16.5 (K) and E18.5 (L). Insets in (A -F) show GFP staining to indicate where Cre was expressed. Scale bars: 50 μm.