ISSN:
0741-0581
Keywords:
Identified neuromuscular junctions
;
Freeze fracture
;
Active zones
;
Synaptic efficacy
;
Ultrastructure
;
Life and Medical Sciences
;
Cell & Developmental Biology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Natural Sciences in General
Notes:
We developed a technique for freeze-fracturing single physiologically identified neuromuscular junctions. This technique permits direct comparison of quantal content with morphological variables such as active zone length per unit terminal length for the same cell. The technique was developed to elucidate the structural basis for variability in transmitter release at the neuromuscular junction. The procedures were as follows: (1) record quantal content by conventional intracellular recordings; (2) mark cells for identification by fluorescent dye injection; (3) fix and stain endplate cholinesterase; (4) glycerinate and remove single fibers from the muscle; (5) draw endplate morphology; (6) freeze-fracture single muscle fibers; (7) examine in a transmission electron microscope; and (8) photograph and measure nerve terminal membrane ultrastructure. We found that approximately 15% of freeze-fractured single muscle fibers exhibited nerve terminal active zones. To demonstrate the usefulness of this technique, physiological and morphological information from an identified junction is presented. Freeze-fracture of identified cells has several advantages over thin sections, which cannot accurately show such things as active zone length, spacing, or intramembrane particles. This technique also has applications to the study of active zone ultrastructure in situations where neurotransmitter release is known to differ from normal levels. In addition, direct correlations between membrane structure and function can be studied in other preparations by this method.
Additional Material:
5 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/jemt.1060040210
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