Fig. 2.

Fig. 2.

Histological and molecular markers show similar timing of early cartilage formation between wild types and fam20b mutants. (A-B′) Lack of Safranin O staining demonstrated that developing ceratohyal cells of wild-type and fam20b mutant zebrafish did not secrete cartilage PGs at 48 hpf. (C-F) Cells in the mesenchymal condensation of both wild types (C,C′,E) and fam20b mutants (D,D′,F) were specified to form cartilage, as evidenced by col2a1a (C-D′) and sox9a (E,F) expression. (G-H′) The spacing between chondrocytes suggested that cartilage PG secretion had occurred in ceratohyal chondrocytes of both wild-type and fam20b mutant zebrafish at 72 hpf, but light Safranin O staining was only observed in wild types. Scale bars: 50 μm. ch, ceratohyal; oc, oral cavity; SafO, Safranin O.