FIG. 7.

Average lengths of neurite growth (±standard error of the mean; SEM) for experiments with a 5-mm cross-channel (A) and 3-mm cross-channel (B). The large error bars are consistent with the spread of the individual points shown in Figs. 4–6, which was linked to day-to-day variations in the growth from explants from a particular chick embryo. These variations were accounted for statistically with a two-way analysis of variance (ANOVA), using the gradient condition as a fixed effect, and the day of the experiment as a random effect, followed by post-hoc testing against the untreated control with Fisher's Least Significant Difference Test to identify which conditions produced accelerated growth (*p<0.05). It is noted that the omnibus ANOVA for IKVAV in 5-mm cross-channels failed to be significant (p=0.110), which precluded subsequent testing of individual conditions against the control. Most conditions with any grafted IKVAV or YIGSR produced growth that was significantly greater than controls, except down the gradient of 0–100% YIGSR in 5-mm channels, and down the gradient of combined peptides in 5-mm channels. It is noteworthy that growth in IKVAV-grafted conditions followed a bi-modal response with respect to average concentration.