Fig. 1. Treatment with RGD-peptides modulates axonal regeneration in organ-cultured CNS. (Ai and Aii) Microphotographs of isolated CNS (dorsal view) that were cultured after receiving a crush to the right internal parietal (RIP) nerve (arrow) in ABS only (i) and ABS + 100 µmol l^–1 GRGDS (ii). Comparison of the two photographs illustrates that the number of labelled right parietal A (RPA) somata was substantially reduced in the presence of GRGDS. (B) Average number of retrograde nickel-lysine labelled RPA somata in preparations that were cultured in ABS only, ABS + 100 µmol l^–1 control peptide SDGRG and ABS + 100 µmol l^–1 GRGDS. (C) Average number of retrograde nickel-lysine labelled RPA somata in preparations that were cultured in ABS only or in the presence of different concentrations of cGRGDSPA (10 nmol l^–1 to 100 µmol l^–1). Treatment with cGRGDSPA had a concentration-dependent biphasic effect on the regeneration of RPA neurons projecting into the RIP nerve. ^***P<0.001.