Figure 6

Analysis of gene expression and fate maps in Fgf8 ^CreER/neo embryos. (A,F) Fgf8, (B, G) Cre, (C, H) Fgf17, and (D, E, I, J) Xgal staining in horizontal sections through E10.5 Fgf8 ^CreER/neo; ROSA26R and control embryos (Tm E8.5). (J,K) are high magnification images of boxed areas in (D,E); arrowheads indicate Xgal⁺ cells outside the Fgf8 ⁺ domain. ISH shown in (F) was left to develop for a long time in order to visualize the low level Fgf8 expression in Fgf8 ^CreER/neo embryos, hence the background on this section is quite high. Asterisk (F) marks the RPC, which is clearly visible in the Cre and Fgf17 ISHs. Note that Cre is expressed in the RPC but not elsewhere in the telencephalon (Horizontal lines in the caudal telencephalon in (G) are artifacts due to tissue folds).