Meeting Abstract

33.1  Monday, Jan. 5  Peripheral sensory cells in the cephalic sensory organs of the pond snail Lymnaea stagnalis WYETH, R.C.*; CROLL, R.P.; St. Francis Xavier Univ.; Dalhousie Univ. rwyeth@stfx.ca

The study of nervous systems in gastropods has focused primarily on central and motor systems, with sensory systems receiving less attention. In particular, peripheral sensory neurons have been only erratically studied across several species. Yet peripheral sensory cells play a crucial role in the neural control of behavior. We are attempting to fill this gap in our understanding of gastropod neuroethology by mapping the peripheral sensory cells in the cephalic sensory organs of Lymnaea stagnalis using backfills, immunohistochemistry, and vital stains. We have found evidence for ciliated catecholaminergic sensory cells, ciliated histaminergic sensory cells, and two classes of nitrergic sensory cells, at least one of which appears to not be ciliated. The histaminergic cells project centrally while the nitregic cells without cilia have no projections. Mapping the projections of the remaining nitrergic cells and the catecholaminergic cells is complicated by the possibility of further classes of non-sensory peripheral neurons with similar neurotransmitters. All four classes of sensory cells have distinctive, non-uniform distributions over the surface of the cephalic sensory organs. None of the morphologies or distributions leads to an obvious hypothesis for either a chemosensory or mechanosensory role. Our next step will thus be to use optical recording experiments to test the cells responses to mechanical and chemical stimuli, and thus link sensory cell morphology to modality for the first time in gastropods. This work opens the possibility of further comparative studies of the peripheral nervous system across gastropods, and can also guide studies of sensory systems roles in the neural control of behavior in Lymnaea and other gastropods.