Neuron-glia interactions in the development of the nervous system

To study the role of neuron-glia interactions during development, I use the developing olfactory system of the moth Manduca sexta, an animal whose sensory periphery is easily accessible and manipulable, and whose olfactory pathway develops during metamorphosis. During this period, olfactory receptor neurons send their axons to the antennal (olfactory) lobe. There the axons induce the formation of structures called glomeruli, which appear in virtually all olfactory systems across the animal kingdom. We have found that glial cells have a vital role in the process of glomerulus formation. Although the receptor axons initiate the formation of glomeruli, the newly forming glomeruli must be stabilized by glial cells, which form a glomeruli. When the glial cell population is severely reduced, the mature antennal lobe lacks glomeruli. The involvement of glial cells in the development of the antennal lobe begins even earlier, however, when the receptor axons first approach the antennal lobe. Just outside the lobe, the axons enter a glia-rich domain where they undergo a sorting process that changes their topographic organization to a chemotopic organization, a process that also must be accomplished by vertebrate olfactory axons. In the moth, the axons fail to sort properly in glia-deficient olfactory systems, strongly suggesting that a glia-neuron interaction underlies the process of axon sorting.