Fig. 2.

Fig. 2.

The chondrogenesis program does not initiate in smb dorsal fins. (A-D) Heterozygous smb mutants were crossed to sox9a:EGFP fish, and offspring were imaged by confocal and transmitted light microscopy during progressive stages of median fin chondrogenesis. (A) In wild-type dorsal fins, the caret indicates initiation of the chondrogenesis program marked by EGFP; white arrowhead indicates stacks of chondrocytes in the developing radials. (B) In smb heterozygous mutants, the asterisk indicates absence of dorsal fin bud mesenchyme and the chondrogenesis program. (C) In wild-type anal fins, the caret indicates initiation of the chondrogenesis program marked by EGFP; white arrowhead indicates stacks of chondrocytes in the developing radials. (D) In smb heterozygous mutant anal fins, the caret indicates initiation of the chondrogenesis program marked by EGFP. White arrowhead indicates stacks of chondrocytes in the developing radials. Fewer individual radials form in mutants. Scale bar: 50 μm.