Cells in the vomeronasal organ express odorant receptors but project to the accessory olfactory bulb
Article first published online: 27 JUL 2006
Copyright © 2006 Wiley-Liss, Inc.
Journal of Comparative Neurology
Volume 498, Issue 4, pages 476–490, 1 October 2006
How to Cite
Lévai, O., Feistel, T., Breer, H. and Strotmann, J. (2006), Cells in the vomeronasal organ express odorant receptors but project to the accessory olfactory bulb. J. Comp. Neurol., 498: 476–490. doi: 10.1002/cne.21067
- Issue published online: 27 JUL 2006
- Article first published online: 27 JUL 2006
- Manuscript Accepted: 22 APR 2006
- Manuscript Revised: 1 MAR 2006
- Manuscript Received: 2 DEC 2005
- accessory olfactory system;
Recent evidence indicates that the vomeronasal organ (VNO) of mice not only responds to pheromones but also to odorants. To analyze whether genes encoding odorant receptors (ORs) are expressed in the VNO, reverse transcriptase-polymerase chain reaction analyses were performed. These led to the identification of 44 different OR genes, comprising class-I and class-II receptors. The genes encoding these receptors were scattered over several gene clusters. The respective OR genes were concomitantly expressed in cells of the main olfactory epithelium (MOE). Although the cells in the MOE were zonally distributed, no such patterns were displayed in the VNO. Cells expressing ORs in the VNO were positive for the TRP2-channel and Gαi, a marker for vomeronasal neurons of the apical layer. In transgenic mice, which coexpress histological markers with the receptor mOR18-2, characteristic morphological differences between cells expressing this receptor in the VNO compared with the MOE became evident. Visualizing the axonal processes of VNO cells expressing distinct ORs revealed that they project to the accessory olfactory bulb (AOB). Axon fibers were visible exclusively in the anterior subdomain; here, they converged into glomerular-like structures positioned at the very rostral tip of the AOB. The findings that a set of ORs is expressed in cells located in the apical layer of the VNO with typical features of VNO sensory neurons that project their axons to the anterior part of the AOB suggest that this population of sensory cells may be considered as a unique facet of the complex chemosensory system. J. Comp. Neurol. 498:476–490, 2006. © 2006 Wiley-Liss, Inc.