Distribution of astroglia in glomeruli of the rat main olfactory bulb: Exclusion from the sensory subcompartment of neuropil

T. Ivo Chao, P. Kása, Joachim R. Wolff

Research output: Contribution to journalArticle

58 Citations (Scopus)

Abstract

During an entire lifetime, sensory axons of regenerating olfactory receptor neurons can enter glomeruli in the olfactory bulb and establish synaptic junctions with central neurons. The role played by astrocytes in this unique permissiveness is still unclear. Glomerular astrocytes have been identified by immunocytochemistry for glial fibrillary acidic protein and S100 proteins at the light and electron microscopic levels. The latter labeling included submicroscopic lamellar and filopodial extensions of astroglial processes. Cell bodies and processes accumulate along the border between juxtaglomerular walls and glomerular neuropil. Within glomeruli, a network of astroglial processes encloses mesh-like neuropil zones devoid of astroglia. Electron microscopy confirmed the division into subcompartments of glomerular neuropil: 1) The 'sensory-synaptic subcompartment' includes all sensory axon terminals and terminal dendritic branches receiving sensory input, whereas astroglia are excluded; 2) in the 'central-synaptic subcompartment,' astroglial processes are intermingled with other neuropil components: dendrites of relay cells and interneurons, dendrodendritic synapses, centrifugal (cholinergic and serotonergic) axons, their axodendritic synapses, and blood vessels. Unevenly distributed astroglial processes in this subcompartment are attached to vascular basal laminae, stem dendrites, and subpopulations of dendrodendritic synapses, especially those colocalised with centrifugal projections ('triadic synapses'). Astroglia- free parts of the 'central' subcompartment contain segments of dendrites and subpopulations of dendrodendritic synapses. Because of the subdivision of the glomerular neuropil into portions with and without glial components, glia do not completely demarcate the border between the 'sensory' and the 'central' subcompartments. Interdigitation between the subcompartments varies among glomeruli and even within a single glomerulus. The mesh width of astroglial networks covaries with numerical relations between sensory and dendrodendritic synapses. This distribution pattern of astrocytes suggests that these glial cells monitor brain-derived effects on olfactory glomerular neuropil rather than olfactory input and that astroglial processes are (re- )arranged accordingly.

Original languageEnglish
Pages (from-to)191-210
Number of pages20
JournalJournal of Comparative Neurology
Volume388
Issue number2
DOIs
Publication statusPublished - Nov 17 1997

Fingerprint

Neuropil
Olfactory Bulb
Astrocytes
Synapses
Dendrites
Neuroglia
Blood Vessels
Axons
Permissiveness
Olfactory Receptor Neurons
S100 Proteins
Glial Fibrillary Acidic Protein
Presynaptic Terminals
Interneurons
Basement Membrane
Cholinergic Agents
Electron Microscopy
Immunohistochemistry
Electrons
Neurons

Keywords

  • GFAP
  • Neuroglia
  • Receptor axons
  • S100 protein
  • Sensory afferents

ASJC Scopus subject areas

  • Neuroscience(all)

Cite this

Distribution of astroglia in glomeruli of the rat main olfactory bulb : Exclusion from the sensory subcompartment of neuropil. / Chao, T. Ivo; Kása, P.; Wolff, Joachim R.

In: Journal of Comparative Neurology, Vol. 388, No. 2, 17.11.1997, p. 191-210.

Research output: Contribution to journalArticle

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