title: The dual origin of the peripheral olfactory system: placode and neural crest.
abstract: BACKGROUND
  The olfactory epithelium (OE) has a unique capacity for continuous neurogenesis, extending axons to the olfactory bulb with the assistance of olfactory ensheathing cells (OECs). The OE and OECs have been believed to develop solely from the olfactory placode, while the neural crest (NC) cells have been believed to contribute only the underlying structural elements of the olfactory system. In order to further elucidate the role of NC cells in olfactory development, we examined the olfactory system in the transgenic mice Wnt1-Cre/Floxed-EGFP and P0-Cre/Floxed-EGFP, in which migrating NC cells and its descendents permanently express GFP, and conducted transposon-mediated cell lineage tracing studies in chick embryos.
  
  
  RESULTS
  Examination of these transgenic mice revealed GFP-positive cells in the OE, demonstrating that NC-derived cells give rise to OE cells with morphologic and antigenic properties identical to placode-derived cells. OECs were also positive for GFP, confirming their NC origin. Cell lineage tracing studies performed in chick embryos confirmed the migration of NC cells into the OE. Furthermore, spheres cultured from the dissociated cells of the olfactory mucosa demonstrated self-renewal and trilineage differentiation capacities (neurons, glial cells, and myofibroblasts), demonstrating the presence of NC progenitors in the olfactory mucosa.
  
  
  CONCLUSIONS
  Our data demonstrates that the NC plays a larger role in the development of the olfactory system than previously believed, and suggests that NC-derived cells may in part be responsible for the remarkable capacity of the OE for neurogenesis and regeneration.
authors.affiliation: Department of Orthopaedic Surgery, Keio University School of Medicine, Shinjuku-ku, Tokyo, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Katoh
authors.forename: Shinsuke
authors.initials: S
authors.lastname: Shibata
authors.forename: Kimiko
authors.initials: K
authors.lastname: Fukuda
authors.forename: Momoka
authors.initials: M
authors.lastname: Sato
authors.forename: Etsuko
authors.initials: E
authors.lastname: Satoh
authors.forename: Narihito
authors.initials: N
authors.lastname: Nagoshi
authors.forename: Takeo
authors.initials: T
authors.lastname: Minematsu
authors.forename: Yumi
authors.initials: Y
authors.lastname: Matsuzaki
authors.forename: Chihiro
authors.initials: C
authors.lastname: Akazawa
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Toyama
authors.forename: Masaya
authors.initials: M
authors.lastname: Nakamura
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Okano
mesh_terms: D000818:Animals; D002642:Chick Embryo; D002999:Clone Cells; D004622:Embryo, Mammalian / Q000166:cytology; D049452:Green Fluorescent Proteins / Q000378:metabolism; D019426:Integrases / Q000378:metabolism; D051379:Mice; D009432:Neural Crest / Q000166:cytology / Q000196:embryology*; D058953:Neural Stem Cells / Q000166:cytology / Q000378:metabolism; D009831:Olfactory Mucosa / Q000166:cytology / Q000196:embryology*; D016133:Polymerase Chain Reaction; D011995:Recombination, Genetic / Q000235:genetics
chemical_list: D049452:Green Fluorescent Proteins; C045073:Cre recombinase; D019426:Integrases