Figure 2. C2 characteristics in Tritonia diomedea.

A. C2_Tri could be identified visually due to its characteristic white soma near the origin of cerebral nerve 1 (CeN1, white arrows). An asterisk (*) labels the statocyst. Only one cerebral-pleural ganglion is shown. B. Filling the C2_Tri soma with Neurobiotin revealed a contralateral axon projection through the anterior cerebral-pedal commissure (not shown) and into the pedal commissure (PP2). The example is a representative image in which the outline of the brain and the axon projection were traced for ease of viewing. C. C2_Tri (arrow) was filled with biocytin (left). It was immunoreactive for both FMRFamide (middle) and SCP_B (right) as shown. D. Backfilling the pedal commissure with biocytin in Tritonia labeled 3–4 neurons near C2_Tri (left). Only the cerebral-pleural ganglion contralateral to the backfilled nerve is shown. FMRFamide-like immunohistochemistry labeled C2_Tri (middle). Combining FMRFamide-like immunoreactivity with the backfill revealed just one neuron, C2_Tri, (right).