(A) CSL+/− and CSL−/− ES cells were differentiated for 8 days under neural differentiation conditions. CSL−/− differentiations do not contain rosettes, as assessed by staining for rosette lumen-specific markers (A) Par3 (Pard3)/CD133 (Prominin)/Actin, (B) Zo-1/phosphorylated myosin light chain (P-MLC)/Actin, (C) N-Cadherin/CD133Actin, and (D) PKCξ stainings. (E–F) Seeding density (1, 1.5 and 2×104 cells/cm2) contributes to the numbers of non-neural (E) and neuronal (F), colonies, per well, obtained from CSL−/− ES cells but no seeding density rescued rosette formation (G) after 8 days of neural differentiation. (H) The lack of rosettes in CSL−/− differentiations is CSL-specific, and not cell-line specific, as the rosette defect seen in CSL−/− ES cells can be rescued by stable re-introduction of CSL. Scale bars in all panels are 50 μm. For separate channels please see Fig. S4.