In the first section of this work, we studied how olfactory sensory neuron axons are guided towards the brain during development. In the second part of this work, we focused on a phenomenon recently discovered by our laboratory: activated olfactory sensory neurons exhibit a decrease in mRNA concentration of the olfactory receptor gene they express upon odorant stimulation. This observation, thought to reflect an adaptation mechanism, was used as a technique to identify which olfactory receptors respond to a given chemical. This method, called DREAM, employs a simple experimental paradigm: a prolonged odorant exposure followed by the quantitation of the olfactory receptor mRNAs extracted from the total olfactory epithelium. In this work, we addressed the mechanistic bases of this stimulation-dependent mRNA downregulation.