Regions of putative acetylcholine receptors at synaptic contacts between neurons maintained in culture and subsequently fixed in solutions containing tannic acid

Spinal cord neurons from 9-day chick embryos were maintained in culture for up to 35 days and then fixed in 4% cacodylate-buffered glutaraldehyde containing 2% tannic acid. After about 15 days in culture a small percentage of the synaptic specializations present were characterized by striking electr...

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Bibliographic Details
Published in:Cell and tissue research 1984, Vol.235 (1), p.85-89
Main Author: BIRD, M. M
Format: Article
Language:English
Subjects:
acetylcholine
Animals
Biological and medical sciences
Cell physiology
Cells, Cultured
Chick Embryo
chick embryos
Coated Pits, Cell-Membrane - analysis
Fixatives
Fundamental and applied biological sciences. Psychology
Hydrolyzable Tannins
Molecular and cellular biology
neurons
Neurons - analysis
Neurotransmission
Receptors, Cholinergic - analysis
spinal cord
Spinal Cord - cytology
Synapses - analysis
synaptic membranes
Synaptic Membranes - analysis
Synaptic Vesicles - analysis
Tannins
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Description
Summary:Spinal cord neurons from 9-day chick embryos were maintained in culture for up to 35 days and then fixed in 4% cacodylate-buffered glutaraldehyde containing 2% tannic acid. After about 15 days in culture a small percentage of the synaptic specializations present were characterized by striking electron-dense striations averaging 15 nm in width, oriented perpendicular to the postsynaptic membrane. These structures increased in frequency with time in culture (to a maximum of about 10% of all synapses in the oldest cultures); they were asymmetrical, protruding approximately 8 nm into the synaptic cleft, and more deeply (approximately 15-18 nm), into the postsynaptic cytoplasm. On the basis of earlier work by Sealock (1980) they are interpreted as concentrations of acetylcholine receptors. Similar membrane differentiations were also seen associated with active-zone areas of a few presynaptic membranes, and the possibility that these represent presynaptic acetylcholine receptors is discussed. Additional observations reported are (1) the presence of striations resembling those seen at the postsynaptic membrane in the membranes of some postsynaptic vesicles, and (2) filamentous links between the striations and cytoskeletal elements of the postsynaptic cell.
ISSN:0302-766X
1432-0878
DOI:10.1007/BF00213727