Fig. 5. Fgf4 and Fgf8 expression is upregulated in mutant forelimbs. (A-L) Fgf8 and (M-X) Fgf4 expression in normal and mutant mouse forelimbs at the somite or embryonic stage indicated. A,B,M,N are lateral views; C,D are distal views, dorsal toward the top; E,F are anterior views; in all other panels (i.e. G-L,O-X), dorsal views are shown with anterior to the left. ^*, aberrant expression. The boxed region in P is shown at high magnification in the inset; boxes in I,J,U,V indicate the regions shown at high magnification in K,L,W,X, respectively. The arrow in G indicates lack of Fgf8 expression over the interdigital region in normal forelimbs; the arrow in H indicates discontinuous Fgf8 expression in the AER in mutant forelimbs.