Morphology of wing mechanoreceptors involved in the wing retraction reflex in the pteropod mollusc Clione limacina

Tactile stimulation of the wings (parapodia) of actively swimming Clione limacina results in inhibition of swimming and retraction of the wings. Electrophysiological evidence suggests that wing mechanoreceptors have central cell bodies and wide innervation fields in the ipsilateral wing. Scanning electron microscopy of expanded wings reveals ciliary cone processes arranged in a pattern that is similar to the electrophysiologically‐determined innervation fields of wing mechanoreceptors. Transmission electron microscopy suggests that the ciliary cone structures are terminal processes of neuron‐like cells. Three‐dimensional reconstructions of serially‐sectioned terminal processes indicate that cell bodies are not found in the wing epithelium or immediately under the epithelium, further supporting the notion that the wing mechanoreceptors have central cell bodies.