Neuronal precursors in the developing olfactory epithelium (OE) produce olfactory receptor, vomeronasal and gonadotropin-releasing hormone neurons, neuronal classes that are essential for chemosensation, social interactions and reproduction. Now, Anthony-Samuel LaMantia and colleagues characterise two distinct populations of neuronal precursors in the mouse OE that give rise to these neuronal types (see p. 2471). They describe a population of slowly dividing, self-renewing precursors mainly in the lateral OE that express high levels of Meis transcription factors and a population of rapidly dividing neurogenic precursors mainly in the medial OE that express high levels of the Sox2 and Ascl1 transcription factors. The Meis dose in the first population reduces Ascl1 expression and neurogenesis, they report, whereas the Sox2 dose in the second population, which is partly controlled by local Fgf8 signalling, promotes OE neurogenesis by suppressing Meis1 and enhancing Ascl1 expression. These insights into the characteristics of OE neuronal precursors should facilitate the identification of the adult OE neural stem cells that generate olfactory receptor and vomeronasal neurons throughout life.
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