The somatotopic organization of the olfactory bulb in elasmobranchs
Article first published online: 27 DEC 2012
Copyright © 2012 Wiley Periodicals, Inc.
Journal of Morphology
Volume 274, Issue 4, pages 447–455, April 2013
How to Cite
Meredith, T. L., Kajiura, S. M. and Hansen, A. (2013), The somatotopic organization of the olfactory bulb in elasmobranchs. J. Morphol., 274: 447–455. doi: 10.1002/jmor.20106
- Issue published online: 6 MAR 2013
- Article first published online: 27 DEC 2012
- Manuscript Accepted: 14 OCT 2012
- Manuscript Revised: 4 SEP 2012
- Manuscript Received: 15 APR 2012
- Marsh Scholarship in Marine Biology, Captain Al Nathan Memorial Scholarship
- Lerner-Gray Grant for Marine Research
- olfactory bulb;
The olfactory bulbs (OBs) are bilaterally paired structures in the vertebrate forebrain that receive and process odor information from the olfactory receptor neurons (ORNs) in the periphery. Virtually all vertebrate OBs are arranged chemotopically, with different regions of the OB processing different types of odorants. However, there is some evidence that elasmobranch fishes (sharks, rays, and skates) may possess a gross somatotopic organization instead. To test this hypothesis, we used histological staining and retrograde tracing techniques to examine the morphology and organization of ORN projections from the olfactory epithelium (OE) to the OB in three elasmobranch species with varying OB morphologies. In all three species, glomeruli in the OB received projections from ORNs located on only the three to five lamellae situated immediately anterior within the OE. These results support that the gross arrangement of the elasmobranch OB is somatotopic, an organization unique among fishes and most other vertebrates. In addition, certain elasmobranch species possess a unique OB morphology in which each OB is physically subdivided into two or more “hemi-olfactory bulbs.” Somatotopy could provide a preadaptation which facilitated the evolution of olfactory hemibulbs in these species. J. Morphol., 2013. © 2012 Wiley Periodicals, Inc.