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Fig. 7
Ex vivo time-lapse imaging revealed extra-hypodermal origins and morphogenetic behaviors of hypodermal mitfa::GFP+ cells and melanophores.
All panels show lateral views of larval trunks and are derived from time-lapse movies of Tg(mitfa::GFP) larvae. Elapsed time (min) at lower right of each panel. (A) mitfa::GFP+ cells differentiated into melanophores (e.g., arrowhead). (B–D) mitfa::GFP+ cells entered the hypodermis during the larval-to-adult transformation. (B) A cell at the dorsal margin of the myotomes extended a long process (arrowhead) into the hypodermis and interacted with processes of a second cell. *, cell body. (C) A long process (arrowhead) preceded emergence of the cell body (*) from the level of the horizontal myoseptum (dotted line). This cell subsequently interacted with a neighboring cell, extended a processes ventrally, and moved in that direction. (D) A cell initially deep within the myotome (*) emerged into the hypodermis. The focal plane changes across panels, from deep within the myotome to the surface of the myotome and hypodermis, where other cells are found already. (E) Death of mitfa::GFP+ cell (*) revealed by fragmentation and cellular debris (arrowheads). (F,G) mitfa::GFP+ cells (F) and melanophores that retain some residual GFP expression (G) proliferating within the hypodermis. Melanophores in G are imaged in a kita mutant (see text for details). See Videos S4, S5, S6, S7, S8, S9, S10, S11, S12, S13, S14, S15, S16.