Synaptic vesicle relationships with the presynaptic membrane as shown by a new method of fast chemical fixation.
Brief vascular perfusion of the rat brain with a mixture of concentrated aldehydes completely insolubilized the brain protein in less than 30 s and yielded excellent ultrastructural preservation. Abundant synaptic vesicles closely and specifically attached to the presynaptic membrane were constantly detected. These vesicles appeared to undergo progressive transformation into amorphous, electron-dense material. No evidence of vesicle exocytosis was detected in the brains perfused in vivo but fixations performed 1 h after death showed abundant exocytotic-like images. The results suggest that the vesicles may not be exocytotically released to the intersynaptic cleft but disintegrate intracytoplasmically in the immediate vicinity of the presynaptic membrane.
González-Aguilar
F
F
Institut fuer Anatomie, Ruhr Universitaet am Bochum, F.R.G.
Rodríguez
J A
JA
Alzola
R H
RH
Lupidio
M C
MC
D000818:Animals; D001921:Brain / Q000648:ultrastructure*; D005089:Exocytosis; D005404:Fixatives; D008854:Microscopy, Electron; D051381:Rats; D013570:Synaptic Membranes / Q000648:ultrastructure; D013572:Synaptic Vesicles / Q000648:ultrastructure*; D014021:Tissue Preservation / Q000379:methods*
D005404:Fixatives