Figure 1

Adult zebrafish pectoral fin denervation assay. a) Pectoral fin innervation. The zebrafish pectoral fin is innervated by both sensory and motor nerves that descend from the spinal cord (SC) and enter the pectoral fin region medially, as a combined brachial plexus (BP) (*). Sensory and motor axons then branch to serve the pectoral muscles and fin rays. Sensorial nerves run both along the intra and inter-ray regions (adapted from [38],[39]). b) Denervation assay. The right pectoral fin was denervated (DEN) by transecting the nerve fibres in the brachial plexus region, while the left fin served as an innervated control (CTRL). In the next day, the right fin was re-denervated to assure total nerve degeneration. After 6–8 hours both fins were amputated and the discarded tissue (*) was collected for ac. α-tub staining. Fish were placed in 33°C water tanks and regeneration was allowed to proceed. Re-denervation took place every day after amputation, to avoid nerve recovery. Regenerates were collected for further analysis at specific time points post-amputation. c,d) Pectoral fin denervation efficiency. Staining for ac. α-tub in whole mount fins shows that nerve ablation at the level of the brachial plexus is efficient to deprive pectoral fins from its innervation. An innervated control fin (c,c’), with bundles of axons running in the inter and intra-ray region (c* - magnification of the boxed region in c), contrasts with a denervated fin (d,d’), with fewer or any presence of the axonal marker ac. α-tub, inside and outside bony rays (d*- magnification of the boxed region in d). The images are a projection of confocal optical slices. Scale bar - 100 μm.