Fig. 3. Effect of NrCAM on RGC axons and growth cones.(A) Overall length of RGC axons of E6 retinal single-cell cultures grown on the indicated substrates. Average length of axons grown on NrCAM/PLL is significantly increased compared with those grown on PLL. Axons grown on NrCAM/Laminin/PLL are significantly longer than those on Laminin/PLL. (B) Proportions of RGC axons grown on the indicated substrates plotted as percentages falling into four length classes. (C) The average growth cone size (i.e. area covered) is not significantly different between axons extending on NrCAM/Laminin/PLL and those on Laminin/PLL. (D) NrCAM causes a small but highly significant increase in the growth cone perimeters on NrCAM/Laminin/PLL compared with Laminin/PLL. (E) Growth cone perimeter divided by the square root of its area, as a measure of protrusions and indentations formed, shows a highly significant increase on NrCAM/Laminin/PLL compared with Laminin/PLL. Error bars represent s.d. * P0.05; *** P0.01.