第9回神経科学学術集会(東京)1985.12.

Morphological difference of mitral cells between the medial and lateral part of the carp olfactory bulb. Neurosci. Res. Suppl. 3: s155.

ICHIRO FUJITA, MASAHIKO SATOU and KAZUO UEDA,
Zoological Institute, University of Tokyo, Bunkyo-ku, Tokyo 113, Japan

The teleost olfactory bulb is functionally differentiated into lateral and medial subdivisions. In the carp, mitral cells in the medial part of the olfactory bulb (mMC) and those in the lateral part (1MC) have their own input fibers,
inhibitory interneurons, projection routes and projection areas (Sheldon, J. Comp. Neurol. 22, 1912; Satou et al., Brain Res., 173, 1979, J. Comp. Physiol. 152, 1983; Fujita et al., Brain Res. 321, 1984). This organization may underlie the
functional separation of the two subdivisions. In the present study, we addressed a question whether there is any morphological difference between the two parts of the bulb. To approach this question, we stained mitral cells using intracellular injection of horseradish peroxidase (HRP) and compared the mMC with the 1MC. Glass micropipettes filled with 5 or 10 % HRP solution were used for intracellular recording and injection of HRP. Mitral cells were identified by their
characteristic responses to electrical stimulation of the olfactory nerve and tracts (Satou et al., 1983). Twenty-eight mitral cells were labeled in 23 carp. The average diameters of somata of the mMC were (31.5 ± 9.6 µm) x (14.0± 3.6 µm)
(n=14) compared to (28.4 ± 10.0 µm) x (13.9 ± 4.3 ~.zm) (n=10) for the 1MC. The number of the first-order dendrites of the mMC was 2.9 ± 1.1 (n=15) compared to 2.9 ± 1.0 for the 1MC (n=10). The thickness of the first-order dendrites at the base of the mMC was 5.6 ± 1.9 um (n=38) , while that of the 1MC was 5.6 ± 2.1 um (n=28). There were no significant differences between the mMC and the 1MC in these parameters. However, the site of origin of the axon differed between the mMC and the 1MC: all the HRP-injected mMC (n=15) gave off axons from the dendrite, while most of the 1MC (5 out of 7 cells) gave off axons from the soma. The results indicate a difference between the medial and lateral parts of the bulb in the site of origin of mitral cell axons.


「コイ嗅球の内側部と外側部の僧帽細胞の間にみられた形態学的差異」

藤田一郎,佐藤真彦*,上田一夫*
生理研高次液性調節,東大理動物*

魚類嗅球の内側部と外側部は機能的に分化している.本研究では,細胞内HRP法を用いてコイの嗅球の内側部と外側部の僧帽細胞(mMCとIMC〉の形態を比較した.細胞体の直径,一次樹状突起の数と太さは,mMCとiMCの閤に差は無かった.しかし,ほとんどのmMCの軸索が樹状突起から生じていたのに対し,ほとんどのIMCは細胞体から軸索を出していた。このように嗅球の内側部と外側部は,機能的のみならず,形態学的にも分化していた.