Fig. 2. Remodeling of skull bone (Alizarin Red) and cartilage (Alcian Blue) during flounder metamorphosis. Skull symmetry first breaks when the cartilaginous right supraorbital bar degrades before the left in pro-metamorphosis (B,B'), allowing passage for the migrating right eye. Right (A-D) and left (A'-D') sides of larvae in different developmental stages. (A,A') Early pre-metamorphosis, left (green arrow) and right (red arrow) supraorbital bars are intact; (B,B') late pro-metamorphosis, right supraorbital bar is degrading (open red arrow) and frontal bones (orange arrowhead) begin to stain with Alizarin Red; (C,C') early metamorphic climax, further degradation of right supraorbital bar and Alizarin Red staining of frontal bones; (D,D') late metamorphic climax, left supraorbital bar has degraded (open green arrow); (E,E') post-metamorphic juvenile, pseudomesial bar (above broken line) is formed. Bars, 0.3 mm.