Olfactory sensory neurons (OSNs) expressing a given @entity8512 ( @entity8512 ) gene project their axons to a few specific glomeruli that reside at recognizable locations in the olfactory bulb. Connecting approximately 1000 populations of OSNs to the approximately 1800 glomeruli of the @entity19 bulb poses a formidable wiring problem. Additional progress in understanding the mechanisms of neuronal connectivity is dependent on knowing how these axonal pathways are organized and how they form during development. Here we have applied a genetic approach to this problem. We have constructed by gene targeting novel strains of @entity19 in which either all OSNs or those that express a specific @entity8512 gene, @entity69520 or @entity69521 , also produce green fluorescent protein (GFP) or a fusion of tau with GFP. We visualized OSNs and their axons in whole mounts with two-photon laser scanning microscopy. The main conclusion we draw from the three-dimensional reconstructions is the high degree of morphological variability of mature glomeruli receiving axonal input from @entity8512 -expressing OSNs and of the pathways taken by the axons to those glomeruli. We also observe that axons of @entity8512 -expressing OSNs do not innervate nearby glomeruli in mature @entity19 . Postnatally, a tangle of axons from @entity69520 -expressing OSNs occupies a large surface area of the bulb and coalesces abruptly into a protoglomerulus at a reproducible stage of development. These results differ in several aspects from those reported for the development of glomeruli receiving input from OSNs expressing the P2 OR, suggesting the need for a more systematic examination of @entity8512 -specific glomeruli.

Structure and emergence of specific olfactory glomeruli in the XXXX .

@entity19 :: ('10090', 'Species') :: ['mice', 'mouse'] @entity69521 :: ('18371(Tax:10090)', 'Gene') :: ['M71'] @entity8512 :: ('258501(Tax:10090)', 'Gene') :: ['OR', 'odorant receptor'] @entity69520 :: ('80706(Tax:10090)', 'Gene') :: ['M72']
@entity19 :: (10090,Species) :: ['mouse']
