Cobalt mapping of neurons with processes in pedal nerves in the pulmonate snailMelampus

Abstract

The central positions of neuron somata with processes in pedal nerves was determined by cobalt chloride backfilling. From six to fourteen, successful backfills were obtained for the paired anterior, medial, posterior and labial-cutaneous pedal nerves. The results, summarized in drawings, revealed the following: 1. Neurons from many central ganglia send axons into pedal nerves. For the pedal nerves studied, neuron somata were found in both pedal ganglia, the ipsilateral pleural ganglion, the ipsilateral and sometimes the contralateral parietal ganglion, the visceral ganglion and one or both of the cerebral ganglia. Buccal ganglia were not included in the study. 2. The distribution patterns for somata marked by backfilling the right and left members of a nerve pair were rough mirror images. Within the pedal ganglia, symmetrical clusters of neurons were found. Some clusters filled only ipsilaterally, and others filled bilaterally but were more strongly represented in the ganglion ipsilateral to the nerve filled. 3. Several large neurons were consistently recognized, and we identified those regions in the pedal ganglia where neurons with processes in each pedal nerve are to be found. This work lays the foundation for the analysis of neuronal control of locomotion by intracellular recording techniques.