The first two columns are as described in Table 1. Columns 3-7 show the percentage of neurons with the following phenotypes. Wild type indicates extended an axon posterolaterally, which turned at the aISN, and clearly extended further; however, in the unrescued lines, even the few in this category did not extend fully to the dorsal muscle field (see Fig. 5). `Posterior extension,truncated' indicates extended an axon posteriorly, including short axons which contacted a nearby RP2 axon. `Anterior extension' indicates extended an axon anteriorly, including short axons which contacted a nearby RP2 axon. `Crossed midline' indicates axon crossed the midline (midline crossing did not occur in any of the other categories); the majority (>90%) of these crossed at the posterior commissure. `No axons' indicates no visible axons. Owing to the necessity of using only one copy of the marker in some lines, the intensity of staining was reduced, especially that of aCC. In cases where pCC neurons were visible but not the corresponding aCC, they were counted as not visible, and were not included in the n (second column).