Structure of intraglomerular dendritic tufts of mitral cells and their contacts with olfactory nerve terminals and calbindin-immunoreactive type 2 periglomerular neurons

Citation
K. Kosaka et al., Structure of intraglomerular dendritic tufts of mitral cells and their contacts with olfactory nerve terminals and calbindin-immunoreactive type 2 periglomerular neurons, J COMP NEUR, 440(3), 2001, pp. 219-235
Citations number
42
Categorie Soggetti
Neurosciences & Behavoir
Journal title
JOURNAL OF COMPARATIVE NEUROLOGY
ISSN journal
00219967 → ACNP
Volume
440
Issue
3
Year of publication
2001
Pages
219 - 235
Database
ISI
SICI code
0021-9967(20011119)440:3<219:SOIDTO>2.0.ZU;2-G
Abstract
Intraglomerular dendritic tufts of Golgi-impregnated and biotinylated dextr an amine (BDA)-labeled mitral cells in the rat main olfactory bulb were ana lyzed in detail. In particular, the relationships of BDA-labeled tufts with olfactory nerve (ON) terminals and processes of calbindin D-28K-immunoreac tive (CB-IR) cells were investigated with confocal laser-scanning light mic roscopic (CLSM) and electron microscopic (EM) analyses. CB-IR cells were ty pe 2 periglomerular cells that restricted their processes in the ON-free (n on-ON) zone of the glomerulus and received few synapses from ON terminals. The mitral tufts varied in complexity, but individual branches were rather simple, smooth processes that bore some branchlets and spines and extended more or less in a straight line or a gentle curve rather than winding tortu ously within glomeruli as though they did not consider the compartmental or ganization, which consisted of ON and non-ON zones that interdigitated in a complex manner with one another. Conventional EM analysis revealed that bo th thin and thick, presumed proximal branches of mitral/tufted cell dendrit ic tufts received asymmetrical synapses from ON terminals. Correlated CLSM- EM analysis confirmed direct contacts between the BDA- and CB-labeled proce sses detected in the CLSM examinations, and synapses were recognized at som e of those sites. Furthermore, ON terminals and CB-IR processes were distri buted on both proximal and distal dendritic branches in a more or less mosa ic pattern. These findings revealed that, on the mitral dendritic tufts, ON terminals and processes of type 2 periglomerular neurons were not clearly segregated proximodistally but, rather, were arranged in a mosaic pattern, which may be important in fine tuning the output from individual glomeruli. J. Comp. Neurol. 440:219-235, 2001. (C) 2001 Wiley-Liss, Inc.