Figure 11

Expression of Pax3 , Wt1 , Wnt2b , Wnt8b , and Wnt1 in the developing cerebral cortex of control and mutant embryos. (A-H) Pax3 immunostaining in control (A, B, E, F) and mutant (C, D, G, H) embryos at embryonic day (E)12.5 (A-D) and E15.5 (E-H). At E12.5, Pax3 positive cells are present in the epithalamus of the control (A, black arrow) and the mutant (D, black arrow). The control cortex is free of Pax3 expression (B). There are a few Pax3 positive cells in the mutant cerebral cortex (D, black arrow). At E15.5, there is no expression of Pax3 by the control cortex (E, F). Pax3 expression is increased in the mutant cerebral cortex (G, H) and Pax3 immunopositive cells are located in upper layers of the cerebral cortex (H). (I, J) Immunostaining for Wt1 (red) in control (I) and mutant embryos (J) at E12.5. Wt1 expression is only seen in the mutant. (K-N) In situ hybridisation for Wnt2b (K, L) and Wnt8b (M, N) transcripts (dark staining) presented as greyscale images in control (K, M) and mutant forebrain (L, N) at E13.5. In control embryos, Wnt2b (K) and Wnt8b (M) expressionis largely restricted to the cortical hem region, with Wnt8b expression extending more dorsally into the medial telencephalon (red arrows). In mutant embryos, Wnt2b (L) and Wnt8b (N) expression is similarly restricted (red arrows) and does not extend into the cerebral cortex. The ubiquitous pale staining is non-specific background. (O, P) qRT-PCR of RNA extracted from E13.5 cerebral cortex of mutant compared to control embryos showing a modest increase in the levels of Wnt8b (O) and a massive increase in the levels of Wnt1 transcripts (P) relative to GAPDH. Student's t-test p-values are indicated above the bars. Error bars are standard error of the mean. All sections are coronal and dorsal is up. Abbreviations: cc, cerebral cortex. Scale bars: (A, C) 200 μm; (B, D, I, J) 50 μm; (E, G) 400 μm; (K-N) 200 μm.