Fig. 2. Larval muscle arm outgrowth and migration. (A) Dorsal view of eight BWMs of an early RP127 trIs25 L1. Muscles 9-15 of the dorsal right quadrant (blue arrows) each BWM extends a single arm (red arrow) to the dorsal cord (yellow arrow). (B) Dorsal view of the same eight BWMs as in A, but in a different animal of the early L2 stage. The four muscles of the dorsal right quadrant (blue arrows) extend 3-4 arms to the dorsal cord. In both A and B, anterior is to the left. (C) Four dorsal left BWMs of an adult RP242 Ex[him-4p::MB::YFP; hmr-1b:: DsRed2; unc-129nsp:: DsRed2]; dpy-5(e61) animal, which serves as the control for muscle arm counts in a lin-6 mutant background. BWM identity numbers are shown, along with the number of muscle arms in brackets. (D) The same four BWMs as in C, but in an RP226 Ex[him-4p::MB::YFP; hmr-1b:: DsRed2; unc-129nsp:: DsRed2]; lin-6(e1466) dpy-5(e61) animal. (E-P) RP235 animals mosaic for [myo-3p::Mb::YFP; unc-25p::DsRed; unc-129nsp::CFP]. Muscle arms are indicated with a red arrowhead. (E-H) The same ventral left muscle 13 from four different animals. (I-L) The same dorsal right muscle 13 from four different animals. (M-P) The same ventral right muscle 13 from four different animals. Scale bars: 20 µm.