Fig. 9

Iridophore disperse laterally to occupy iridophore-devoid regions.

(a–c) Iridophores (white arrowheads, Tg(sox10:mRFP)) extend to the empty segment on the left and increase in number. (d–k) Gap closure in an animal lacking iridophores in six segments at 22 dpf (numbered 1–6). Red dashed lines indicate the original borders of the gap. Small arrows in d–h: larval melanophores remain stable within the gap. (e) Iridophores that are present outside the gap begin to invade the iridophore-devoid segments and within a day, iridophores can be seen in segment 1 and 6. (f–h) By lateral movement, iridophores recover in segments 1–3 and 5–6, only the segment 4 remains devoid of iridophores. (i) The first light stripe, X0 lacks iridophores in the segment 4 and remains interrupted. Corresponding region in the newly formed light stripe also lacks iridophores (red arrowheads). The dark stripe region does not develop sufficient melanophores and subsequently iridophores begin to migrate vertically (big red arrow) invading the dark stripe region. (j,k) Vertically migrating iridophores lead to interruption of the dark stripe region by the light stripe region. SL, standard length of fish. Scale bars,100 μm.