Neuronal gap junctions in the rat main olfactory bulb, with special reference to intraglomerular gap junctions.
The structural features of neuronal gap junction-forming processes in the rat olfactory bulb were analyzed electron microscopically. Gap junctions were present in glomeruli and extraglomerular regions. In extraglomerular regions, mitral/tufted cell somata, dendrites and axon hillock-initial segments made gap junctions and mixed synapses with interneuronal processes, some of which were confirmed to be GABA positive. In glomeruli gap junctions were encountered mainly between mitral/tufted cell dendrites and diverse types of processes; a small population of them were conclusively identified as periglomerular cell dendrites. Gap junction-forming processes frequently received synapses from olfactory nerve terminals, suggesting that they could be type 1 periglomerular cells. However, the majority were GABA negative or only faintly positive and none were tyrosine hydroxylase positive, indicating that they were different from previously reported type 1 periglomerular cells. Furthermore serial sectioning analyses revealed that the majority of those processes forming gap junctions with mitral/tufted dendrites were smooth cylindrical and had few presynaptic sites, indicating that they were different from previously described periglomerular cells. These findings revealed that mitral/tufted cells make gap junctions with diverse types of neurons; and some of these gap junction-forming processes originated from some types of periglomerular cells but others from hitherto uncharacterized neuron type(s).
Kosaka
Toshio
T
Department of Anatomy and Neurobiology, Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan. kosaka@a3rd.med.kyushu-u.ac.jp
Kosaka
Katsuko
K
D000818:Animals; D017629:Gap Junctions / Q000737:chemistry / Q000648:ultrastructure*; D008297:Male; D009474:Neurons / Q000737:chemistry / Q000648:ultrastructure*; D009830:Olfactory Bulb / Q000737:chemistry / Q000648:ultrastructure*; D051381:Rats; D017208:Rats, Wistar; D005680:gamma-Aminobutyric Acid / Q000032:analysis
D005680:gamma-Aminobutyric Acid