Figure 1

In situ RNA hybridization on horizontal sections in wild-type, Fgf8^Null/Neoand Fgf15^-/-E9.5 embryos. (a, b) Fgf15 (a) and Fgf8 (b) expression in adjacent sections of a wild-type embryo. (c-d') Fgf15 expression in wild-type (c) and Fgf8^Null/Neoembryos (d). Higher magnifications of (c, d) are shown in (c', d'). (e-n) Expression analysis in wild-type and Fgf15 mutant embryos showing adjacent sections of CoupTF1 (e, f), Fgf8 (g, h), Spry2 (i, j), Erm (k, l) and cMyc (m, n). Arrowheads in (a, b): rostral midline that is Fgf8⁺ and Fgf15^-; the midline becomes Fgf15⁺ in Fgf8^Null/Neo(d, d'). Arrow in (d): loss of Fgf15 expression in the midbrain of the Fgf8^Null/Neomutant. Arrows in (e, f): reduced CoupTF1in Fgf15^-/-. Bar in (a) is 200 μm.