title: Secretagogin-containing neurons in the mouse main olfactory bulb.
abstract: Secretagogin (SCGN) is a recently discovered calcium binding protein of the EF hand family. We studied the structural features of SCGN-positive neurons in the mouse main olfactory bulb (MOB). SCGN-positive neurons were localized throughout layers but clustered in the glomerular layer (GL), mitral cell layer (MCL) and granule cell layer (GCL). They were heterogeneous, including numerous juxtaglomerular neurons, granule cells, small to medium-sized neurons in the external plexiform layer (EPL), and a few small cells in the ependymal/subependymal layer. Calretinin and/or tyrosine hydroxylase occasionally colocalized in SCGN-positive juxtaglomerular neurons. Calretinin also frequently colocalized in SCGN-positive EPL and GCL neurons. Morphologically some of juxtaglomerular SCGN-positive neurons were classical periglomerular cells, whereas others were apparently different from those periglomerular cells, although they were further heterogeneous. Some extended one slender process into a glomerulus which passed the glomerulus and further penetrated into another nearby glomeruli, and thus their dendritic processes spanned two or three or more glomeruli. We named this type of juxtaglomerular neurons "transglomerular cells." With the stereological analysis we estimated total number of juxtaglomerular SCGN-positive neurons at about 80,000/single MOB. The present study revealed the diversity of SCGN-positive neurons in the mouse MOB and their particular structural properties hitherto unknown.
authors.affiliation: Department of Health Sciences, Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan.
authors.forename: Katsuko
authors.initials: K
authors.lastname: Kosaka
authors.forename: Toshio
authors.initials: T
authors.lastname: Kosaka
mesh_terms: D000818:Animals; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009474:Neurons / Q000166:cytology / Q000378:metabolism* / Q000648:ultrastructure; D009830:Olfactory Bulb / Q000166:cytology / Q000378:metabolism* / Q000648:ultrastructure; D064046:Secretagogins / Q000378:metabolism*
chemical_list: C576557:SCGN protein, mouse; D064046:Secretagogins
keywords: 4′,6-diamidino-2-phenylindole; 5-bromo-2′-deoxyuridine; 5-ethynyl-2′-deoxyuridine; ABC; AOB; BDA; BSA; BrdU; CB; CLSM; CR; Calcium binding protein; Cy3; Cy5; DAB; DAPI; EM; EPL; EdU; FITC; GCL; GL; IPL; Local circuit neuron; MCL; MNL; MOB; MTL; NOS; OB; ON; ONL; Olfactory system; PB; PBS; PV; PaB; Periglomerular cell; RMS; SCGN; SEL; Short-axon cell; TH; VN; VNL; accessory olfactory bulb; avidin–biotin-peroxidase complex; biotinylated dextran amine; bovine serum albumin; calbindin D28k; calretinin; confocal laser scanning microscope; diaminobenzidine tetrahydrochloride; electron microscope; ependymal/subependymal layer; external plexiform layer; fluorescein isothiocyanate; glomerular layer; granule cell layer; indocarbocyanine; indodicarbocyanine; internal plexiform layer; main olfactory bulb; mitral and tufted cell layer of the accessory olfactory bulb; mitral cell layer; myelinated nerve layer of the accessory olfactory bulb; nitric oxide synthase; olfactory bulb; olfactory nerve layer; olfactory nerve/olfactory nerve terminal; pacific blue; pacific blue-conjugated streptavidin; parvalbumin; phosphate buffer; phosphate buffered saline; rostral migratory stream; secretagogin; stPaB; tyrosine hydroxylase; vomeronasal nerve; vomeronasal nerve layer