Fig. 9. Dorsal view of cephalic ganglia regeneration in G. tigrina after injection of GtPax6A/GtPax6B dsRNA mixture, visualized by whole-mount neuropeptide FMRFamide immunoreactivity pattern at different regenerative stages. (A,C) After 5 (A) and 9 days (C) of regeneration, new transversal commissures produced from the amputated old nerve cords and differentiating the proximal cephalic ganglia (arrows) can be observed in water-injected controls. The distal part of the new cephalic ganglia is organizing an arch-shaped structure that connects the nerve cords (arrowhead). (B,D) No abnormal cephalic ganglia regeneration is apparent in corresponding head-regenerating fragments subsequent to injection of GtPax6A/GtPax6B dsRNA mixture. Regenerating eyes appear as small black spots of similar size in both C and D. (E,F) After 20 days from cutting, a complete regeneration of the cephalic ganglia can be observed. No differences in the CNS pattern can be seen between a water-injected control (E) and an dsRNA-injected planarian (F). Scale bars: 0.5 mm.