Fig. 4.

Neural projections and neuropeptide mapping of the right parietal neurons innervating the copulatory apparatus of Lymnaea stagnalis. The enlarged parietal ganglion (in the box) shows the heptapeptide-expressing neurons (HP neurons, solid circles) and the nonheptapeptide-expressing neurons (nonHP neurons, open circles). The dark parts in the central nervous system (CNS) correspond to the three other neuronal clusters that are relevant in this context (anterior and ventral lobes of the right cerebral ganglion and the Ib cluster of the right pedal ganglion, also shown in Fig. 1). The right panel shows six superimposed stimuli (stim.) of the same neuron and the response as it was measured in the three different nerve branches (NP1, NP2, NP3). As indicated above the traces, the left neuron only had an axon projecting into NP2, the right neuron had axons in both NP1 and 3. Abbreviations: NP penis nerve, NP1, NP2 and NP3, the three branches of the penis nerve; P penis, PP preputium