Fig. 3. (A) Summary of extrinsic innervation of the zebrafish gill illustrating formation of a nerve bundle composed of nerve fibres emanating from the BN of the gill arch that gives rise to a nerve plexus surrounding the eFA. Fibres of the nerve plexus associate with NECs (green) and MRCs (blue) and extend out to the respiratory lamellae (indicated by arrows). (B) Intrinsic innervation showing nerve endings of SPNs and DPNs terminating at the base of the eFA, and extension of SPN and DPN nerve fibres towards NECs and ChNs (with varicose processes), respectively. BN, branchial nerve; eBA, efferent branchial artery; eFA, efferent filament artery; ChN, chain neuron; DPN, deep proximal neuron; MRC, mitochondria-rich cell; NEC, neuroepithelial cell, SPN; superficial proximal neuron. (Modified from Jonz and Nurse, 2003.)