Organization and distribution of glomeruli in the bowhead whale olfactory bulb
- Published
- Accepted
- Subject Areas
- Evolutionary Studies, Neuroscience, Zoology, Anatomy and Physiology, Histology
- Keywords
- brain, brain, baleen whale, cetacea, olfactory marker protein, Mysticeti
- Copyright
- © 2014 Kishida et al.
- Licence
- This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. For attribution, the original author(s), title, publication source (PeerJ PrePrints) and either DOI or URL of the article must be cited.
- Cite this article
- 2014. Organization and distribution of glomeruli in the bowhead whale olfactory bulb. PeerJ PrePrints 2:e740v1 https://doi.org/10.7287/peerj.preprints.740v1
Abstract
Although modern baleen whales still possess a functional olfactory systems that includes olfactory bulbs, cranial nerve I and olfactory receptor genes, their olfactory capabilities have been reduced profoundly. This is probably in response to their fully aquatic lifestyle. The glomeruli that occur in the olfactory bulb can be divided into two non-overlapping domains, a dorsal domain and a ventral domain. Recent molecular studies revealed that all modern whales have lost olfactory receptor genes and marker genes that are specific to the dorsal domain, and that a modern baleen whale possess only 60 olfactory receptor genes. Here we show that olfactory bulb of bowhead whales (Balaena mysticetus, Mysticeti) lacks glomeruli on the dorsal side, consistent with the molecular data. In addition, we estimate that there are more than 4,000 glomeruli in the bowhead whale olfactory bulb. Olfactory sensory neurons that express the same olfactory receptor in mice generally project to two specific glomeruli in an olfactory bulb, meaning that ratio of the number of olfactory receptors : the number of glomeruli is approximately 1:2. However, we show here that this ratio is not applicable to whales, indicating the limitation of mice as model organisms for understanding the initial coding of odor information among mammals.
Author Comment
This is a submission to PeerJ for review.
Supplemental Information
Figure S1
A coronal section of the OB of bowhead whale 09B11 (section 32). Glomeruli are labeled with anti-OMP antibody, and are indicated with arrows. Scale bar, 1000um.
Figure S2
A coronal section of the OB of bowhead whale 09B11 (section 143). Glomeruli are labeled with anti-OMP antibody, and are indicated with arrows. Scale bar, 1000um.
Figure S3
A coronal section of the OB of bowhead whale 09B11 (section 195). Glomeruli are labeled with anti-OMP antibody, and are indicated with arrows. Scale bar, 1000um.
Figure S4
A coronal section of the OB of bowhead whale 09B11 (section 391). Glomeruli are labeled with anti-OMP antibody, and are indicated with arrows. Scale bar, 1000um.
Figure S5
A coronal section of the OB of bowhead whale 09B11 (section 518). Glomeruli are labeled with anti-OMP antibody, and are indicated with arrows. Scale bar, 1000um.
Figure S6
A horizontal section of the OB of bowhead whale 09B14 (section 134). Glomeruli are labeled with anti-OMP antibody. Scale bar, 1000um. Left, anterior; right, posterior.
Table S1
Number of glomeruli on approx. every 10th slide. Nos. of glomeruli with slide nos. in parentheses are estimated by taking an average between the glomeruli-counted sections in front and in the rear.