Compromised FP specification in Gas1−/− embryos is exacerbated by reducing Shh dosage. Antibody detection of FoxA2 (red; A,C,E,G,I) and Shh (green; B,D,F,H,J) in forelimb-level sections of E10.5 Gas1; Shh embryos. Inset in F denotes variable FP expression of Shh seen in Gas1−/− embryos. Double staining of wild-type (K,L,M), Gas1+/− (N,O,P), and Gas1−/− (Q,R,S) embryos with FoxA2 (red) and Nkx2.2 (green). (T) Quantitation of FoxA2, Nkx2.2 double-positive cells. Error bars represent the mean ± SD of three different embryos. P-values calculated from comparison of wild-type and Gas1−/− data by two-tailed Student’s t-test are listed. (N.S.) Not significant (p > 0.5). Bar: A, 50 μm.