Fig. 4. Chondroitinase digestion of pericellular proteoglycans of migrating Schwann cells at the DRG frontier results in a shift to lower mobilities. (A-D) Extended treatment with chondroitinase ABC (40 hours) revealed cells radiating from the DRG centre (towards lower right, phase-contrast view in A), many of which were S100-positive Schwann cells (B) bearing pericellular 3B3-immunopositivity (C). (D) Merged image of B and C. (E-H) Although control treatment with the heat-inactivated enzyme similarly revealed cells radiating from the DRG centre (towards mid-right, phase-contrast view in E), none of the S100-positive cells (F) showed pericellular 3B3-immunopositivity (G). (H) Merged image of F and G. The bar chart (I) shows the shift towards lower mobility among Schwann cells at the migration front during time-lapse video recording of cultures undergoing a further 3-hour treatment with (+) chondroitinase ABC compared with those without (-) the enzyme. Mobility ranges are classified high at >2.3 µm/minute, intermediate at 1.5-2.3 µm/minute and low at <1.5 µm/minute. Results are the mean ± s.e.m. of triplicate DRG experiments prepared for time-lapse video recording (^*P=0.46; ^**P=0.29). (J,K) One of these DRGs is shown both under light microscopy to reveal C6st1 mRNA signals (J) and under phase-contrast optics to reveal cell profiles (K). Cells that had been mapped for mobility measurements were numbered as indicated. The corresponding video clip and profile of cell mobility are shown in supplementary material Movie 2 and Fig. S3. Bars, 100 µm (A-H) and (J,K).