UNASSIGNED: In @entity238 olfactory sensory neurons (OSNs) establish synapses with projection neurons (PNs) and local interneurons within @entity1315 ( @entity1315 ) glomeruli. Substantial knowledge regarding this circuitry has been obtained by functional studies, while ultrastructural evidence of synaptic contacts is scarce. To fill this gap we studied serial sections of three glomeruli using electron microscopy. Ectopic expression of a membrane-bound peroxidase allowed us to map synaptic sites along @entity6841 dendrites. Our data proves for the first time that each of the three major types of @entity1315 neurons is both pre- and postsynaptic to the other two types as previously indicated by functional studies. @entity6841 dendrites carry a large proportion of output synapses, with approximately one output per every three input synapses. Detailed reconstructions of @entity6841 dendrites showed that these synapses are distributed unevenly, with input and output sites partially segregated along a proximal-distal gradient and the thinnest branches carrying solely input synapses. Moreover, our data indicate synapse clustering as we found evidence of @entity2343 . @entity6841 output synapses exhibited T-shaped presynaptic densities, mostly arranged as tetrads. In contrast, output synapses from putative OSNs showed elongated presynaptic densities in which the T-bar platform was supported by several pedestals and contacted as many as 20 postsynaptic profiles. We also discovered synaptic contacts between the putative OSNs. The average synaptic density in the glomerular neuropil was about two synapses/  m(3) . These results are discussed with regard to current models of olfactory glomerular microcircuits across species. This article is protected by copyright. All rights reserved.

Synaptic circuitry of identified neurons in the @entity1315 of XXXX .

@entity1315 :: ('MESH:D004833', 'Disease') :: ['antennal lobe', 'AL'] @entity2343 :: ('MESH:D007635', 'Disease') :: ['dendritic tiling of PN dendrites'] @entity238 :: ('7227', 'Species') :: ['Drosophila melanogaster'] @entity6841 :: ('MESH:C565820', 'Disease') :: ['PN']
@entity238 :: (7227,Species) :: ['Drosophila melanogaster']
