Figure 1

Pax6^-/- cells derived from mutant ES cells integrate in Pax6^-/- ↔ Pax6^+/+ chimeras and show predictably abnormal phenotypes. (A-D) In these E14.5 chimeras, mutant cells are recognized by a brown nuclear spot, which is the result of DNA-DNA in situ hybridization for a reiterated β-globin transgene. (A,B) Sections of the cerebral cortex showing clusters of Pax6^-/- cells in the subventricular zone; these cells are positive for Mash1 (grey staining in B). (C,D) In the eye, chimeras show abnormal retinal morphologies (boxed area) exhibiting extreme segregation between wild type and mutant cells, similar to abnormalities reported previously in aggregation chimeras [20]. The arrowhead in D indicates an example of the boundary between an area of mutant and an area of wild type cells with abnormal retinal folding. Scale bars: A,B,D = 50 μm; C = 100 μm.