Complex mechanoreceptors inTritonia diomedea

Abstract

1. A cluster of small neurons located in each cerebral ganglion ofTritonia diomedea responds to mechanical and chemical stimulation of receptive areas of the ipsilateral oral veil and anterior foot (Figs. 2, 3). 2. These neurons respond to several types of chemical stimuli, but appear to be excited most strongly by extracts of sea whip,Virgularia sp. (Fig. 3, Table 1), a normal prey ofTritonia. 3. These neurons appear to be primary mechano-receptors with receptive endings in the ipsilateral foot (accessed via PdN 1) and oral veil (accessed via both CeN 2 and CeN 3; Fig. 4). Receptive fields of different branches of the same receptor (Fig. 4) and of different receptors (Fig. 5) overlap in the oral veil. 4. The mechanoreceptors are not primary chemoreceptors but receive excitation via chemical synapses from chemoreceptors located in the periphery (Fig. 6). At least some of this synaptic input is peripheral in origin. 5. Ipsilateral mechanoreceptors are electrically coupled to one another by non-rectifying electrical junctions (Fig. 7). No contralateral inputs or interactions between receptors were found. 6. A model is presented for the anatomy and wiring of these complex receptors (Fig. 8).