The Olfactory System as a Model to Study Axonal Growth Patterns and Morphology In Vivo

Thomas Hassenklöver, Ivan Manzini
2014 Journal of Visualized Experiments  
Citation: Hassenklöver, T., Manzini, I. The Olfactory System as a Model to Study Axonal Growth Patterns and Morphology In Vivo. Abstract The olfactory system has the unusual capacity to generate new neurons throughout the lifetime of an organism. Olfactory stem cells in the basal portion of the olfactory epithelium continuously give rise to new sensory neurons that extend their axons into the olfactory bulb, where they face the challenge to integrate into existing circuitry. Because of this
more » ... icular feature, the olfactory system represents a unique opportunity to monitor axonal wiring and guidance, and to investigate synapse formation. Here we describe a procedure for in vivo labeling of sensory neurons and subsequent visualization of axons in the olfactory system of larvae of the amphibian Xenopus laevis. To stain sensory neurons in the olfactory organ we adopt the electroporation technique. In vivo electroporation is an established technique for delivering fluorophore-coupled dextrans or other macromolecules into living cells. Stained sensory neurons and their axonal processes can then be monitored in the living animal either using confocal laser-scanning or multiphoton microscopy. By reducing the number of labeled cells to few or single cells per animal, single axons can be tracked into the olfactory bulb and their morphological changes can be monitored over weeks by conducting series of in vivo time lapse imaging experiments. While the described protocol exemplifies the labeling and monitoring of olfactory sensory neurons, it can also be adopted to other cell types within the olfactory and other systems. Video Link The video component of this article can be found at 11, 12 . Using in vivo time lapse imaging, it is also suitable to supervise the glomerular connections of single mature sensory neurons, and to monitor the evolution of the axonal projection patterns of immature sensory neurons 12 . The described protocol can be applied to investigate the structure and formation of olfactory circuits in the intact animal and can be adapted to other cell types within the olfactory and other neuronal systems.
doi:10.3791/52143 pmid:25406975 pmcid:PMC4353389 fatcat:cmeisjpdifgrvme5hn74pv3koi