Fig. 3. Patterns of gene expression that distinguish anterior and posterior regions of the telencephalon are for the most part maintained the in Fgfr1-deficient mice. RNA in situ hybridization on sagittal sections of E12.5 telencephalons using Emx2 (A,A') and Pax6 (B,B') probes. In control embryos (A,B), Emx2 and Pax6 form opposing gradients in the cerebral cortex. Emx2 and Pax6 gradients are also established in mutants (A',B'). Scale bar: 0.4 mm. (C,C') Cdh8 expression at E16.5; the anterior domain of Cdh8 expression is reduced in mutants (C') compared with control (C) (arrowheads). (D,D') Ephrin A5 expression at P0; in control animals (D), ephrin A5 is expressed most strongly in the presumptive sensorimotor cortex (Mackarehtschian et al., 1999) and this location of strongest expression is unchanged in Foxg1-Cre;Fgfr1^flox/flox mutants (D'). Scale bar for C-D': 0.6 mm.