title: Morphological study on the olfactory systems of the snapping turtle, Chelydra serpentina.
abstract: In this study, the olfactory system of a semi-aquatic turtle, the snapping turtle, has been morphologically investigated by electron microscopy, immunohistochemistry, and lectin histochemistry. The nasal cavity of snapping turtle was divided into the upper and lower chambers, lined by the sensory epithelium containing ciliated and non-ciliated olfactory receptor neurons, respectively. Each neuron expressed both Gαolf, the α-subunit of G-proteins coupling to the odorant receptors, and Gαo, the α-subunit of G-proteins coupling to the type 2 vomeronasal receptors. The axons originating from the upper chamber epithelium projected to the ventral part of the olfactory bulb, while those from the lower chamber epithelium to the dorsal part of the olfactory bulb. Despite the identical expression of G-protein α-subunits in the olfactory receptor neurons, these two projections were clearly distinguished from each other by the differential expression of glycoconjugates. In conclusion, these data indicate the presence of two types of olfactory systems in the snapping turtle. Topographic arrangement of the upper and lower chambers and lack of the associated glands in the lower chamber epithelium suggest their possible involvement in the detection of odorants: upper chamber epithelium in the air and the lower chamber epithelium in the water.
authors.affiliation: Laboratory of Veterinary Anatomy, Iwate University, 3-18-8 Ueda, Morioka, Iwate 020-8550, Japan; United Graduate School of Veterinary Sciences, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan. Electronic address: nakamuta@iwate-u.ac.jp.
authors.forename: Nobuaki
authors.initials: N
authors.lastname: Nakamuta
authors.affiliation: Laboratory of Veterinary Anatomy, Iwate University, 3-18-8 Ueda, Morioka, Iwate 020-8550, Japan.
authors.forename: Shoko
authors.initials: S
authors.lastname: Nakamuta
authors.affiliation: Faculty of Education, Shizuoka University, 836 Ohya, Shizuoka 422-8529, Japan.
authors.forename: Hideaki
authors.initials: H
authors.lastname: Kato
authors.affiliation: Laboratory of Veterinary Anatomy, Iwate University, 3-18-8 Ueda, Morioka, Iwate 020-8550, Japan; United Graduate School of Veterinary Sciences, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan.
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Yamamoto
mesh_terms: D000818:Animals; D001369:Axons / Q000378:metabolism; D044385:GTP-Binding Protein alpha Subunits / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000378:metabolism*; D007150:Immunohistochemistry; D008854:Microscopy, Electron; D009830:Olfactory Bulb / Q000033:anatomy & histology / Q000378:metabolism; D018034:Olfactory Receptor Neurons / Q000378:metabolism* / Q000648:ultrastructure; D014426:Turtles / Q000033:anatomy & histology*
chemical_list: D044385:GTP-Binding Protein alpha Subunits; C084618:olfactory G protein subunit alpha olf; D019204:GTP-Binding Proteins
keywords: Electron microscopy; Immunohistochemistry; Lectin histochemistry; Olfactory bulbs; Olfactory organs; Reptiles