Histological properties of the nasal cavity and olfactory bulb of the Japanese jungle crow Corvus macrorhynchos.
The nasal cavity and olfactory bulb (OB) of the Japanese jungle crow (Corvus macrorhynchos) were studied using computed tomography (CT) and histochemical staining. The nasal septum divided the nasal cavity in half. The anterior and maxillary conchae were present on both sides of the nasal cavity, but the posterior concha was indistinct. A small OB was present on the ventral surface of the periphery of the cerebrum. The OB-brain ratio--the ratio of the size of the OB to that of the cerebral hemisphere--was 6.13. The olfactory nerve bundles projected independently to the OB, which appeared fused on gross examination. Histochemical analysis confirmed the fusion of all OB layers. Using a neural tracer, we found that the olfactory nerve bundles independently projected to the olfactory nerve layer (ONL) and glomerular layer (GL) of the left and right halves of the fused OB. Only 4 of 21 lectins bound to the ONL and GL. Thus, compared with mammals and other birds, the jungle crow may have a poorly developed olfactory system and an inferior sense of olfaction. However, it has been contended recently that the olfactory abilities of birds cannot be judged from anatomical findings alone. Our results indicate that the olfactory system of the jungle crow is an interesting research model to evaluate the development and functions of vertebrate olfactory systems.
Yokosuka
Makoto
M
Department of Comparative and Behavior Medicine, Faculty of Veterinary Medicine, Nippon Veterinary and Life Science University, Musashino, Tokyo 180-8602, Japan. mayokosuka@nvlu.ac.jp
Hagiwara
Akiko
A
Saito
Toru R
TR
Tsukahara
Naoki
N
Aoyama
Masato
M
Wakabayashi
Yoshihiro
Y
Sugita
Shoei
S
Ichikawa
Masumi
M
D000818:Animals; D046368:Crows / Q000033:anatomy & histology* / Q000502:physiology*; D007564:Japan; D037102:Lectins / Q000032:analysis / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009296:Nasal Cavity / Q000033:anatomy & histology*; D009830:Olfactory Bulb / Q000033:anatomy & histology* / Q000378:metabolism; D009832:Olfactory Nerve / Q000033:anatomy & histology / Q000378:metabolism; D011485:Protein Binding; D011784:Quail; D014057:Tomography, X-Ray Computed
D037102:Lectins