Quantification of PQR posterior neurite growth cone filopodia defects. (A) A micrograph demonstrating how filopodia number and growth cone perimeter was quantified. Asterisks mark filopodial protrusions (<0.5 μm in width). The red dashed line is a tracing of the distal 3 μm of the growth cone perimeter. (B) The y-axis represents the average number of filopodia present on the PQR posterior neurite growth cone at 7 to 8 h after hatching. Error bars represent standard error of the mean. arx-2(ok1269M+) and arx-7(ok1118M+) displayed significantly fewer filopodia than wild type (* P < 0.0001). Cell-specific expression of the arx-7(+) in PQR via the Pgcy-32::arx-7(+):: gfp transgene rescued filopodia defects of arx-7(ok1118M+) (** P < 0.0001). unc-115(ky275) was not significantly different from wild type (P = 0.51), but did significantly enhance arx-2(ok1269M+) and arx-7(ok1118M+) (*** P = 0.003 and 0.007, respectively). unc-34(e951) displayed significantly fewer filopodia than wild type (**** P < 0.0001). (C) Growth cone perimeter (in microns) is on the y-axis. Error bars represent standard error of the mean. arx-7(ok1118M+) and unc-115(ky275) had reduced growth cone perimeter compared to wild type (* P < 0.001) whereas unc-34 did not (NS = not significant).