Fig. 2. Lecticans inhibit the formation of microprocesses and of complex growth cones by TN-R. (A,B) Tectal cells were cultured on a contactin 1 substrate and treated for 6 hours with increasing amounts of (A) aggrecan (5-20 µg/ml) and (B) chondroitinase-ABC-treated aggrecan (20 µg/ml), brevican or neurocan in the absence or presence of TN-R (10 µg/ml) as indicated. For quantitative analysis of neuronal morphology see Materials and Methods. The percentage of neurons belonging to each morphological category was calculated and typical examples are shown. Error bars represent s.e.m. The blocking effect of aggrecan on TN-R-induced microprocess formation and growth cone enlargement is dose-dependent, mediated by the core protein and similar to that of other lecticans.