Fig. 1. Sfrp1^-/-;Sfrp2^-/- embryos display shortening of the thoracic region and limb morphogenesis abnormality. (A) Gross morphology of Sfrp1^-/-;Sfrp2^-/- mutant (left) and control (right) embryos at E14.5. Arrows indicate the craniofacial abnormality; arrowheads indicate edematous defects. Scale bar: 1 mm. (B-E) Cartilage staining in control (B,D) and Sfrp1^-/-;Sfrp2^-/- (C,E) embryos at E15.5. The number of thoracic vertebrae was reduced in Sfrp1^-/-;Sfrp2^-/- embryos. Although vertebrae numbers were normal, the sides of vertebrae were reduced in the lumbar and sacral regions. Arrowhead, C7 vertebra; double arrowhead, T1 vertebra; single arrow, L1 vertebra; double arrow, S1 vertebrae; C1, atlas. Scale bar: 1 mm. (F-I) Extra digits (arrowhead) on the hindlimb of Sfrp1^-/-;Sfrp2^-/- embryos (G) at E14.5, and the skeletal pattern of the hindlimb in control (H) and Sfrp1^-/-;Sfrp2^-/- (I) embryos at E15.5. T, tail. Scale bars: 500 µm in F,G; 200 µm in H,I. (J,K) Fgf8 expression in the limb bud of control (J) and Sfrp1^-/-;Sfrp2^-/- (K) embryos at E10.5. Arrows indicate the extra stripes of Fgf8 expression in the ventral surface of the hindlimb bud. A, anterior; P, posterior. Scale bar: 400 µm.