Post-Embryonic Nerve-Associated Precursors to Adult Pigment Cells: Genetic Requirements and Dynamics of Morphogenesis and Differentiation
Shown are the relative frequencies of cells entering the hypodermis in time-lapse movies of trunks derived from wild-type larvae (N = 127 larvae, 1220 mitfa::GFP+ total cells examined) during different periods of pigment pattern metamorphosis (very early, 6.4–6.6 SSL; early, 6.6–6.8 SSL; middle, 6.8–7.6 SSL). Cells newly arrived in the hypodermis (n = 644) were classified as migrating over the dorsal or ventral margins of the myotomes (DV), emerging from the vicinity of the horizontal myoseptum (HM) and lateral line, or emerging from within the myotomes (M), tyically along vertical myosepta. Individuals were binned by stage and bar widths are proportional to the average numbers of newly appearing hypodermal mitfa::GFP+ cells per larva, normalized to cells mm−2 day−1 (mean±SE above bars). The relative frequencies of cells arising from different sources differed between stages (χ2 = 20.0, d.f. = 4, P<0.0001), with cells increasingly likely to emerge from within the myotomes as compared to migrating over the dorsal or ventral margins of the myotomes.