Fig. 1.

Netrin-A and frazzled mutant Drosophila embryos show defects in v'ch1 dendrite position and orientation. (A-I) Single hemisegments of mAb 22C10-immunostained embryos (A,D,G), DiI-labelled v'ch1 neurons (B,E,H) and diagrams showing site of exit and orientation of the v'ch1 dendrite in wild-type (C), NetA^p (F) and fra³ (I) mutants. Arrows in A, D and G show the v'ch1 dendrite, white dots show the lch5-5 neuron, and the asterisk in E shows the v'ch1 scolopale cell. (C) The mean and range of dendrite exit position (green dot and dashes on circle, representing the v'ch1 cell body) and orientation (unbroken and broken green lines, respectively) in wild-type embryos (n=41) are shown. Equivalent positions and orientations for the axon are shown in blue. (F,I) Each red line in these diagrams represents the site of exit and orientation of individual dendrites that lie outside the wild-type range of positions and orientations (green). In this and all subsequent figures anterior is up and dorsal is to the right. Scale bars: 10 μm.