title: The olfactory bulb and the number of its glomeruli in the common marmoset (Callithrix jacchus).
abstract: The olfactory system has been well studied in mammals such as mice and rats. However, few studies have focused on characterizing this system in diurnal primates that rely on their sense of smell to a lesser extent due to their ecological environment. In the present study, we determined the histological organization of the olfactory bulb in the common marmoset (Callithrix jacchus). We then constructed 3-dimensional models of the glomeruli of the olfactory bulb, and estimated the number of glomeruli. Olfactory glomeruli are the functional units of olfactory processing, and have been investigated in detail using mice. There are approximately 1800 glomeruli in a mouse hemibulb, and olfactory sensory neurons expressing one selected olfactory receptor converge onto one or two glomeruli. Because mice have about 1000 olfactory receptor genes, it is proposed that the number of glomeruli in mammals is nearly double that of olfactory receptor genes. The common marmoset carries only about 400 intact olfactory receptor genes. The present study revealed that the number of glomeruli in a marmoset hemibulb was approximately 1500-1800. This result suggests that the number of glomeruli is not positively correlated with the number of intact olfactory receptor genes in mammals.
authors.affiliation: Laboratory of Brain Structure, Tokyo Metropolitan Institute of Medical Science, Kamikitazawa, Setagaya, Tokyo, Japan. Electronic address: moriya-kk@igakuken.or.jp.
authors.forename: Keiko
authors.initials: K
authors.lastname: Moriya-Ito
authors.affiliation: Laboratory of Brain Structure, Tokyo Metropolitan Institute of Medical Science, Kamikitazawa, Setagaya, Tokyo, Japan.
authors.forename: Ikuko
authors.initials: I
authors.lastname: Tanaka
authors.affiliation: Laboratory of Brain Structure, Tokyo Metropolitan Institute of Medical Science, Kamikitazawa, Setagaya, Tokyo, Japan.
authors.forename: Yoshitomo
authors.initials: Y
authors.lastname: Umitsu
authors.affiliation: Center for Basic Technology Research, Tokyo Metropolitan Institute of Medical Science, Kamikitazawa, Setagaya, Tokyo, Japan.
authors.forename: Masumi
authors.initials: M
authors.lastname: Ichikawa
authors.affiliation: Laboratory of Brain Structure, Tokyo Metropolitan Institute of Medical Science, Kamikitazawa, Setagaya, Tokyo, Japan.
authors.forename: Hironobu
authors.initials: H
authors.lastname: Tokuno
mesh_terms: D000818:Animals; D002144:Callithrix / Q000033:anatomy & histology*; D005260:Female; D008297:Male; D009830:Olfactory Bulb / Q000033:anatomy & histology*
keywords: Accessory olfactory bulb; Glomerulus; Nonhuman primate; Olfactory receptor gene