Fig. 7. Aggrecan induces retraction of tectal cell neurites after TN-R pretreatment. (A-C) Tectal cells were cultured on a contactin 1 substrate and pretreated for 20 hours with TN-R (10 µg/ml). Control medium (A), aggrecan (20 µg/ml) (B) or chondroitinase-ABC-treated aggrecan (20 µg/ml) (C) were added under time-lapse control, and phase-contrast images were taken at the indicated time points. Bar, 10 µm. (D) For quantification, the percentage of neurites that retracted within 4 hours was calculated (see Materials and Methods). The protein in solution and the incubation periods are given below. Error bars represent s.e.m. Aggrecan and chondroitinase-ABC-treated aggrecan induce strong neurite retraction in cells pretreated with TN-R compared with control cells.