Iridophore development in the posterior trunk. (A-D) Wild type. Iridophores appear first at the horizontal myoseptum and grow in density. In the melanophore region, they maintain their bluish reflection, whereas their colour turns golden in the dense interstripe regions. Melanophores of the larval lateral stripe that are still present along the horizontal myoseptum (A) are cleared from this area during stages PR and SP (B,C). (E-H) rse mutant. Iridophores grow in number but remain always below the level of wild type. (I-L) shd mutant. No iridophores develop. Metamorphic melanophores avoid the region of X0, but the clearance of larval melanophores from this area is considerably delayed compared with wild type. ao aorta. Stages: PB, pelvic fin bud. PR, pelvic fin ray. SP, squamation onset posterior. J+, juvenile+. Scale bars: 250 μm.