Stereological quantification of olfactory receptor neurons in mice

Kawagishi, Kyutaro; Ando, Masao; Yokouchi, Kumiko; Sumitomo, Norimi; Karasawa, Mika; Fukushima, Nanae; Moriizumi, Tetsuji

doi:10.1016/j.neuroscience.2014.04.050

Cited by 32 publications

(27 citation statements)

References 23 publications

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“…If not all 1,100 OR genes are expressed in OSNs, the total number of OR‐expressing OSNs from these estimates will be lower. Our estimate is lower than the estimate of ∼9,400 OSNs expressing on average a given OR gene in the ∼10 million mature, OMP‐expressing OSNs in 8‐week‐old C57BL/6J mice (Kawagishi et al, ). But the age difference of 3 versus 8 weeks is substantial, and the fraction of OMP‐expressing OSNs that does not express an OR gene is not known.…”

Section: Discussioncontrasting

confidence: 68%

Linear correlation between the number of olfactory sensory neurons expressing a given mouse odorant receptor gene and the total volume of the corresponding glomeruli in the olfactory bulb

Bressel

Khan

Mombaerts

2015

J of Comparative Neurology

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Chemosensory specificity in the main olfactory system of the mouse relies on the expression of ∼1,100 odorant receptor (OR) genes across millions of olfactory sensory neurons (OSNs) in the main olfactory epithelium (MOE), and on the coalescence of OSN axons into ∼3,600 glomeruli in the olfactory bulb. A traditional approach for visualizing OSNs and their axons consists of tagging an OR gene genetically with an axonal marker that is cotranslated with the OR by virtue of an internal ribosome entry site (IRES). Here we report full cell counts for 15 gene‐targeted strains of the OR‐IRES‐marker design coexpressing a fluorescent protein. These strains represent 11 targeted OR genes, a 1% sample of the OR gene repertoire. We took an empirical, “count every cell” strategy: we counted all fluorescent cell profiles with a nuclear profile within the cytoplasm, on all serial coronal sections under a confocal microscope, a total of 685,673 cells in 56 mice at postnatal day 21. We then applied a strain‐specific Abercrombie correction to these OSN counts in order to obtain a closer approximation of the true OSN numbers. We found a 17‐fold range in the average (corrected) OSN number across these 11 OR genes. In the same series of coronal sections, we then determined the total volume of the glomeruli (TGV) formed by coalescence of the fluorescent axons. We found a strong linear correlation between OSN number and TGV, suggesting that TGV can be used as a surrogate measurement for estimating OSN numbers in these gene‐targeted strains. J. Comp. Neurol. 524:199–209, 2016. © 2015 Wiley Periodicals, Inc.

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Section: Discussioncontrasting

confidence: 68%

Linear correlation between the number of olfactory sensory neurons expressing a given mouse odorant receptor gene and the total volume of the corresponding glomeruli in the olfactory bulb

Bressel

Khan

Mombaerts

2015

J of Comparative Neurology

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“…Male and female mice have the same number of OSNs in the olfactory epithelium50, so the difference presumably arises physiologically, potentially from differences in the odor selectivity of OSNs (Fig. 1F) or differences in OSN response kinetics (Fig.…”

Section: Discussionmentioning

confidence: 99%

Differences in peripheral sensory input to the olfactory bulb between male and female mice

Kass

Czarnecki

Moberly

et al. 2017

Sci Rep

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Female mammals generally have a superior sense of smell than males, but the biological basis of this difference is unknown. Here, we demonstrate sexually dimorphic neural coding of odorants by olfactory sensory neurons (OSNs), primary sensory neurons that physically contact odor molecules in the nose and provide the initial sensory input to the brain’s olfactory bulb. We performed in vivo optical neurophysiology to visualize odorant-evoked OSN synaptic output into olfactory bub glomeruli in unmanipulated (gonad-intact) adult mice from both sexes, and found that in females odorant presentation evoked more rapid OSN signaling over a broader range of OSNs than in males. These spatiotemporal differences enhanced the contrast between the neural representations of chemically related odorants in females compared to males during stimulus presentation. Removing circulating sex hormones makes these signals slower and less discriminable in females, while in males they become faster and more discriminable, suggesting opposite roles for gonadal hormones in influencing male and female olfactory function. These results demonstrate that the famous sex difference in olfactory abilities likely originates in the primary sensory neurons, and suggest that hormonal modulation of the peripheral olfactory system could underlie differences in how males and females experience the olfactory world.

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“…68 Different contexts may affect sniffing according to sex: in chimpanzees, for example, males sniff more than females during social settings, while females sniff more during feeding. 70 Overall, the total number of OR genes exceeds 1000 in the mouse and rat, and a recent comparison of placental mammals showed a range of intact OR expression from 296 in orangutans to nearly 2000 in African elephants, with humans at 396. In terms of overall number of OSNs, there seems to have been no direct comparison of men vs women; in mice, there is no difference in the estimate of OSN number between the sexes.…”

Section: Main Olfactory Epitheliummentioning

confidence: 99%

Sex differences in main olfactory system pathways involved in psychosexual function

Cherry

Baum

2019

Genes Brain and Behavior

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We summarize literature from animal and human studies assessing sex differences in the ability of the main olfactory system to detect and process sex-specific olfactory signals ("pheromones") that control the expression of psychosexual functions in males and females. A case is made in non primate mammals for an obligatory role of pheromonal signaling via the main olfactory system (in addition to the vomeronasalaccessory olfactory system) in mate recognition and sexual arousal, with male-specific as well as female-specific pheromones subserving these functions in the opposite sex.Although the case for an obligatory role of pheromones in mate recognition and mating among old world primates, including humans, is weaker, we review the current literature assessing the role of putative human pheromones (eg, AND, EST, "copulin"), detected by the main olfactory system, in promoting mate choice and mating in men and women. Based on animal studies, we hypothesize that sexually dimorphic effects of putative human pheromones are mediated via main olfactory inputs to the medial amygdala which, in turn, transmits olfactory information to sites in the hypothalamus that regulate reproduction.K E Y W O R D S accessory olfactory system, chemosignal, human, main olfactory bulb, main olfactory epithelium, main olfactory system, medial amygdala, mouse, pheromone, sex difference, sexual behavior

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Stereological quantification of olfactory receptor neurons in mice

Cited by 32 publications

References 23 publications

Linear correlation between the number of olfactory sensory neurons expressing a given mouse odorant receptor gene and the total volume of the corresponding glomeruli in the olfactory bulb

Linear correlation between the number of olfactory sensory neurons expressing a given mouse odorant receptor gene and the total volume of the corresponding glomeruli in the olfactory bulb

Differences in peripheral sensory input to the olfactory bulb between male and female mice

Sex differences in main olfactory system pathways involved in psychosexual function

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