The ultrastructure of the cat olfactory bulb

Willey, T. Joe

doi:10.1002/cne.901520302

Cited by 106 publications

(26 citation statements)

References 34 publications

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“…These cells are probably also not Schwann cells even though Willey (1973) has referred to them as such. Schwann cells are typically enclosed by basal laminae and collagen fibers (Causey, 1960;Glees and Meller, 1968;Peters et al, 1976;Carlsen and Behse, 1980), whereas ensheathing cells were not apposed to basal laminae except in those places where they formed part of the external glial limiting membrane.…”

Section: Identification Of Ensheathin-g Cells In Thementioning

confidence: 99%

The glial cells in the nerve fiber layer of the rat olfactory bulb

1984

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In mammals the olfactory receptor neurons are the only ones that are known to undergo continuous cell renewal in the adult animal. This means that the axon of each newly formed neuron must grow into the olfactory bulb to find its appropriate target cell. It is presumed that astrocytes ensheath the olfactory axons as they course through the nerve fiber layer of the bulb even though the cells in question differ ultrastructurally from typical astrocytes. The purpose of the present study was to examine the glial cells in the nerve fiber layer of the rat olfactory bulb in an effort to resolve this apparent discrepancy. Two morphologically distinct types of glial cell were found in the nerve fiber layer. One type, which resembled the typical astrocytes that are present in other areas of the central nervous system, contained bundles of filaments in an electron-lucent cytoplasm. These cells also formed endfeet on blood vessels and formed part of the external glial limiting membrane. They did not, however, ensheath the olfactory axons. The cytoplasm of the other type of glial cell was denser than that of typical astrocytes and contained fewer filaments, which were seldom grouped into bundles. These cells also formed part of the glial limiting membrane at the surface of the bulb and were the only ones that ensheathed the olfactory axons. It is concluded that the cell ensheathing the olfactory axons in the nerve fiber layer of the rat olfactory bulb is a morphological variant of the typical astrocyte.(ABSTRACT TRUNCATED AT 250 WORDS)

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Section: Identification Of Ensheathin-g Cells In Thementioning

confidence: 99%

The glial cells in the nerve fiber layer of the rat olfactory bulb

1984

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“…Electron microscopic studies of the olfactory bulb have revealed reciprocal synapses between mitral cell dendrites and the peripheral processes of granule cells (Fig. 1B and C) (Hirata, 1964;Andres, 1965;Rall et al 1966;Price & Powell, 1970a;Reese & Shepherd, 1972;Willey, 1973). Moreover, it has been reported that nearly all the synapses found on mitral cell dendrites and somata, except in or around the glomerular region, are reciprocal synapses with the peripheral processes of granule cells (Price & Powell, 1970b; Reese & Shepherd, 1972).…”

Section: Introductionmentioning

confidence: 99%

An intracellular study of dendrodendritic inhibitory synapses on mitral cells in the rabbit olfactory bulb.

Mori¹,

Takagi²

1978

The Journal of Physiology

125

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“…Early electron microscopic studies focused on neuronal elements, especially intraglomerular synapses, and noted the presence only of astroglial tissue components (Reese and Brightman, 1965;Powell, 1971b, 1972;Willey, 1973). Later, astrocytes were identified morphologically by Golgi staining, histochemically by silver-carbonate impregnation, and immunohistochemically by glial fibrillary acidic protein (GFAP) antibodies.…”

mentioning

confidence: 99%

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

1997

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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 colocalized 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.

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The ultrastructure of the cat olfactory bulb

Cited by 106 publications

References 34 publications

The glial cells in the nerve fiber layer of the rat olfactory bulb

The glial cells in the nerve fiber layer of the rat olfactory bulb

An intracellular study of dendrodendritic inhibitory synapses on mitral cells in the rabbit olfactory bulb.

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

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