Fig. 7.

MiP retains its ventral process in the absence of muscle pioneers. A, An intracellularly labeled control MiP at 24 h in a living embryo; this cell had retracted its ventral process and extended an axon dorsally. B, An intracellularly labeled experimental MiP in a living embryo at 48 h in the absence of muscle pioneers. The ventral process extended beyond the distal limit of the common pathway (broken line) onto the CaP pathway and had not retracted. Ectopic branching (arrows) was observed in 6 of 27 embryos at 48 h. Scale bar, 10 μm.