Fig. 3

Hypothalamic Slit expression is maintained while thalamic Robo2 expression is reduced in Pax6 ^−/− embryos at E13.5. a–d In situ hybridisation at E14.5 shows Slit1 and Slit2 mRNA expression at the hypothalamus in Pax6 ^+/+ embryos (arrows, a,c,d). e–h In situ hybridisation shows that Slit1 and Slit2 mRNA expression is maintained in the hypothalamus in Pax6 ^−/− embryos (arrows e, g, h). i, j Quantitative RT-PCR on tissue from the hypothalamus shows no significant difference in Slit1 (i) and Slit2 (j) mRNA expression between Pax6 ^+/+ and Pax6 ^−/− embryos (Student’s t-tests, n = 5 WT and 5 mutants). k–n In situ hybridisation for Robo1 and Robo2 shows mRNA expression of both genes within the thalamus of Pax6 ^+/+ embryos (arrows k,m,n). o–r In situ hybridisation in Pax6 ^−/− embryos shows that Robo1 expression is still present within the thalamus although the expression domain appears reduced in size (arrow o). In situ hybridisation for Robo2 shows that the expression is reduced within the thalamus of Pax6 ^−/− embryos, particularly at rostral levels (q). s, t Quantitative RT-PCR performed on the whole thalamus shows that while there is no difference in Robo1 expression between Pax6 ^+/+ and Pax6 ^−/− embryos (s; Student’s t-test, n = 5 WT and 5 mutants), Robo2 mRNA expression is significantly reduced in Pax6 ^−/− embryos compared to Pax6 ^+/+ embryos (t; Student’s t-test, n = 5 WT and 5 mutants, p = 0.03). Scale bars: 500 μm