| Research Abstract |
In the present study, various examinations were carried out to clarify the details of olfactory information transmision mechanism in the vertebrates. In Xenopus laevis, the main and lower chambers were lined by the olfactory epithelium and vomer onasal organ, respectively, and the middle chamber was lined by a specific sensory epithelium, the middle chamber epithelium. These three olfactory receptor organs showed the different expression patterns of glycoconjugates with each other. Judging from the absence of associated olfactory gland and the difference in fine structure of receptor cells, the middle chamber epithelium was suggested to be an olfactory organ to detect odoriferous molecules in water. In addition, the olfactory epithelium, middle chamber epithelium, vomeronasal organ projected to the dorsal region of the main olfactory bulb (MOB), ventral region of the MOB, and the accessory olfactory bulb, respectively. These findings suggested the presence of three independent olfactory pathways in Xenopus laevis. Then, olfactory glomeruli of the hamster MOB showed the differential expression patterns of glycoconjugates with 13 kinds of lectins. These results suggested that individual glomeruli were different with each other in the kind and volume of sugar residues from the viewpoint of probability. Lastly, the three olfactory receptor organs of rats, i.e., olfactory epithelium, vomer onasal organ, and septal olfactory organ of Masera (MO), developed in common from the primitive olfactory epithelium lining the embryonic nasal pit. In the case of the MO, the primitive olfactory epithelium lining the nasal septum transformed to the respiratory epithelium around the MO, and the remaining primitive olfactory epithelium differentiated to the MO on the nasal septum. Further, results by bio-imaging were not satisfactory in the present study.
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