When our noses pick up a scent, whether the aroma of a sweet rose or the sweat of a stranger at the gym, two types of sensory neurons are at work in sensing that odor or pheromone. These sensory neurons are particularly interesting because they are the only neurons in our bodies that regenerate throughout adult life—as some of our olfactory neurons die, they are soon replaced by newborns. Just where those neurons come from in the first place has long perplexed developmental biologists. Previous hypotheses about the origin of these olfactory nerve cells have given credit to embryonic cells that develop into skin or the central nervous system, where ear and eye sensory neurons, respectively, are thought to originate. But biologists at the California Institute of Technology (Caltech) have now found that neural-crest stem cells—multipotent, migratory cells unique to vertebrates that give rise to many structures in the body such as facial bones and smooth muscle—also play a key role in building olfactory sensory neurons in the nose. "Olfactory neurons have long been thought to be solely derived from a thickened portion of the ectoderm; our results directly refute that concept," says Dr. Marianne Bronner, the Albert Billings Ruddock Professor of Biology at Caltech and corresponding author of a paper published online in the open-access journal eLIFEon March 19, 2013 that outlines the findings. A related article (U. of Sheffield) was published online in eLIFE on March 26, 2013. eLIFE is backed by three of the most prestigious biomedical research funders in the world: the Howard Hughes Medical Institute, the Max Planck Society, and the Wellcome Trust.
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