Pax6 expression levels are increased in Foxg1-/-;Pax77 telencephalon compared to Foxg1-/- telencephalon. (A) Levels of total Pax6 mRNA (endogenous Pax6 and human PAX6) in the telencephalon of E12.5 Foxg1-/-;Pax77 embryos and Foxg1-/- embryos determined by real-time quantitative RT-PCR and normalised against GAPDH mRNA levels (mean ± s.e.m, n = 3 in each case). Total Pax6 mRNA levels are significantly increased in Foxg1-/-;Pax77 telencephalon compared to Foxg1-/- telencephalon (Student's t-test, P < 0.05). (B,C) Coronal sections through one hemisphere of the forebrain of Foxg1-/- (B) and Foxg1-/-;Pax77 (C) embryos at E12.5, showing the expression of total Pax6 (endogenous Pax6 and human PAX6). Pax6 levels appear increased in Foxg1-/-;Pax77 compared to Foxg1-/- telencephalon, although the lateralhigh to mediallow gradient is not restored.