Fig. 3. (A) Schematic representation of the fish olfactory system, portraying cell bodies and dendrites of olfactory neurons within the olfactory epithelium. Axons of olfactory neurons extend via the olfactory nerve to the olfactory bulb where they synapse with post-synaptic bulbar neurons (after Hara, 1986). The broken line indicates the theoretical boundary separating the olfactory bulb from the olfactory nerve. (B) Sagittal whole-body autoradiogram showing ¹⁰⁹Cd accumulation after 7-day Cd exposure followed by 2-day depuration in control water. (C) Corresponding whole-body tissue section. OR, olfactory rosette; ON, olfactory nerve; OB, olfactory bulb.