Fig. 1. Schematic representation of the gill arches, pseudobranch and their innervation. (A) Ventral view of the organization of the gill arches (numbers 1 to 4) and pseudobranch (PB) in teleosts. VA, ventral aorta; DA, dorsal aortae. Based on Weichert (Weichert, 1967). (B) Illustration of the organization of gill filaments and lamellae in a typical teleost fish. Large arrows indicate the flow of water through the gills, and small arrows indicate the flow of blood. aFA, afferent filament artery; eFA, efferent filament artery; F, filament; L, lamellae. (Modified from Jonz et al., 2004.) (C) Left lateral view of the nerve supply to the gill arches and pseudobranch from cranial nerves (VII, IX and X). Branchial structures are innervated by postganglionic divisions (red) of pre-trematic (pr) and post-trematic (po) rami.