NEURON-GLIA INTERACTIONS IN THE SORTING ZONE REGION OF THE MOTH OLFACTORY PATHWAY

picture of Amanda Levy presenting his/her poster: NEURON-GLIA INTERACTIONS IN THE SORTING ZONE REGION OF THE MOTH OLFACTORY PATHWAY

Amanda Levy , Lynne Oland

NEURON-GLIA INTERACTIONS IN THE SORTING ZONE REGION OF THE MOTH OLFACTORY PATHWAY

The precise wiring that characterizes the adult nervous system depends in part on sorting axons from different areas or modalities.  This sorting requirement is particularly obvious in the mammalian and insect olfactory systems, which have a similar organization.  Sensory cells sensitive to particular odorants are distributed across the sensory epithelium rather than being grouped together by subtype, and all of the axons of the cells that share the same sensitivity target the same subcompartment of the olfactory lobe in the brain.  Thus the axons must be sorted by subtype somewhere in the olfactory pathway.  The moth, Manduca sexta, is ideal as a model because the sorting is accomplished in a discrete, glia-rich region of the olfactory nerve rather than in the olfactory bulb, as occurs in mammals.  The axons rapidly change their trajectory in this region and become fasciculated with axons that share the same sensitivity, but only in the presence of the glial cells.  Thus, the key to understanding the sorting process during development is to understand glial-axonal interactions.

To increase our understanding of the sorting zone ‘s glial network structure, I am creating a high resolution, three-dimensional model of glial processes at two stages of development during the period of axon ingrowth.  The data set consists of 1,500 70-nm-thick aligned serial sections imaged with the electron microscope.  Glial processes and nuclei were traced and rendered as smoothed contours, producing a three-dimensional model of the glial network. At stage 7, the glial network is more extensive than expected, with glial cells forming thin vellate sheets that extend around small bundles of sensory axons.  The model will be extended by adding the contours of axonal growth cones to determine their spatial relationship to glial cells and to suggest hypotheses about the nature of the signaling molecules used for neuron-glia interactions. Acknowledgments go out to Patty Jansma and Marvin Landis for their help in this project. Funding provided by NIH NIDCD: 008597.

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