Fig. 7. Effects of Smed-netrin1 and netrin2 RNAi in the regeneration and maintenance of the planarian CNS. (A-B) Normal cephalic ganglia (A) and VNCs (B) regenerate after Smed-netrin1 RNAi. Arrowhead points to the commissure connecting the cephalic ganglia. (C-D) After Smed-netrin2 RNAi the anterior commissure is thickened (arrowhead in C) and the ganglia are wider than normal. The VNCs regenerate in a disorganized meshwork of projections (D). (E) Posterior uninjured region of an anterior regenerating animal showing ectopic processes (arrowhead) between the VNCs after Smed-netrin2 RNAi. (F) Newly regenerated tail region showing abnormal regeneration of the VNCs after Smed-netrin2 RNAi. All regenerants were fixed 2 weeks after amputation. (G-H) Disorganized neural pattern with ectopic axonal processes in the cephalic (G) and post-pharyngeal (H) regions of intact planarians 2 weeks after Smed-netrin2 RNAi. B,D,E,G and H are single confocal planes; A shows confocal projections through 5.6 µm; C,F show confocal projections through 4.8 µm. (A-D,F-H) Anterior to the left. (E) Anterior to the top. Scale bar: 100 µm. cg, cephalic ganglia.