ISSN:
0741-0581
Keywords:
Quick freezing
;
Synaptic vesicles
;
Cholinergic nerve terminals
;
Electric organ
;
Life and Medical Sciences
;
Cell & Developmental Biology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Natural Sciences in General
Notes:
The limitations of chemical fixation in permitting the 1:1 quantitative correlations required for convincing ultrastructural explanations of cell biological processes are noted. We describe techniques for obtaining highly reproducible direct quick freezing on the polished surface of pure copper bars dipping into a static dewar of liquid N2. The importance and the ease of testing and obtaining bounce suppression with commerically available equipment is emphasized. Artefacts caused by tissue damage and bad freezing are illustrated, and a hitherto unrecognized population of presynaptic membrane attached vesicles is described in Torpedine electric organ. Between 15 and 20% of the synaptic vesicles are attached to ca. 30% of the cytoplasmic face of the presynaptic terminal membrane. There is a close correlation between the occurrence of such attachments and the application of electrocyte basal lamina to the external face. We suggest that these vesicles are the ‘membrane operators,’ ‘vesigates,’ and ‘highly active subpopulation’ of vesicles whose existence has been invoked to explain biochemical data in other laboratories. We further speculate that relatively selective Ca pumping by this immediately submembranous population leads to displacement of acetylcholine (ACh) and reloading with newly synthesized ACh. The preferential release of the latter would then be expected.
Additional Material:
16 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/jemt.1060010103
