FIGURE 1

Giant dopamine-containing neurone in the left pedal ganglia of Planorbis corneus. The upper photograph is a whole mount of the two ganglia showing the giant dopamine neurone (G, as dopamine produces a green fluorescence with the Falk–Hillarp method) in the left ganglion. The other fluorescing cells are yellow and contain 5-HT (serotonin). The lower photograph is a section through the left pedal ganglion showing the large dopamine neurone with its axon. This neurone was used in subsequent metabolic and electrophysiological studies (Berry & Cottrell, 1973).