Fig. 8. Fgf8^Null/Neo and Fgf8^TelKO mutants have progressive reduction of telencephalic Nkx2.1 expression. Whole-mount in situ hybridization on dissected E10 rostral neural tube using probes for Nkx2.1 (A,A',A'') and Shh (B,B') shows that expression of both genes is reduced in the telencephalic domains of Fgf8^Null/Neo and Fgf8^TelKO embryos. Shh expression in the telencephalon of the Fgf8^TelKO mutant was not assessed because previous work demonstrated that loss of Nkx2.1 function in the telencephalon prevents Shh induction in the telencephalon (Sussel et al., 1999). Arrows in B,B' indicate Shh expression in the basal telencephalon. HT, hypothalamus; MGE, medial ganglionic eminence.