blast Growth Factor Receptors, which are present on glial cells during critical stages of development. FGFRs represent an additional possible signaling partner linking glia and axons reciprocally via 
Neuroglian and MFasII. Work by several Glial FGFRs in Glia-Neuron ” Signaling antennal lobes of the brain where they end in structures called glomeruli and synapse with antennal lobe neurons. Two classes of AL neurons, local interneurons and projection neurons, have their cell bodies in clusters called the lateral and medial groups, which reside outside of the antennal lobe neuropil. B: Labeling of an untreated female antennal lobe at stage 7 with an antibody to M. sexta Fasciclin II and a nucleic acid dye makes clear the major changes in ORN axon fasciculation and direction a short distance into the sorting zone, with axons exiting the sorting zone in large MFas II-positive bundles. Projection depth = 15 mm. C: A single glomerulus, showing the relationship of ORN axon terminals and AL neuron dendrites. ORN axons form a nerve layer around the outside of the antennal lobe neuropil, then turn sharply and extend through the glial layer and branch in the outer portion of a glomerulus in the glomerular layer. The cell bodies and processes of neuropil glial cells form a nearly complete envelope around each glomerulus. Panels A and C adapted from. In the current study, we find that FGFRs are present and activated on SZ, NP, and AN glia “
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“during developmental stages important in axon ingrowth and sorting and in the formation of olfactory glomeruli in the antennal lobe. Pharmacologic blockade of FGFR activation leads to the absence of migration by NP, but not SZ or AN, glial cells. Blockade of glial FGFRs also leads to aberrant ORN axon outgrowth. Because we find no evidence for FGFRs on ORNs, this suggests that activation of glial FGFRs is important in glia-to-ORN signaling. As it does in many other systems, FGFR activation also appears to be essential for glial cell survival, as blockade leads to widespread glial cell loss at later stages. Materials and Methods Animals Manduca sexta were reared from eggs on an artificial diet in a laboratory colony essentially as described by Sanes and Hildebrand. The adult antennal system develops during metamorphosis, when the animal changes from larva to moth. This phase can be divided into 18 stages, each lasting 14 days. Animals were staged according to features, such as eye pigmentation and leg development, R-roscovitine chemical information visible through the cuticle under fiber-optic illumination as described by Tolbert et al. and Oland and Tolbert. Removal of antennal input In some animals, the antennal lobe on one side was deprived of ORN axon input throughout development, using surgical methods described previously. Briefly, animals at stage 1 of adult development were anaesthetized by exposure to CO2. The cuticle covering the base of one antenna was removed and the underlying part of the antennal anlage removed with forceps. The opening was ” then filled with melted wax to prevent ORN axons from surviving distal receptor neurons from extending toward the brain, and the animals were returned to the rearing facility and allowed to develop under standard conditions. Because ORN axons do not project contralaterally, the antennal lobe on the operated side received no input from ORNs. The antenna on the opposite side was not disturbed and therefore received normal afferent input. Primary antibodies for immunocytochemistry When possible, antibodies
