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Updated: Aug 7, 2026

Quantitative Analysis of Synaptic Vesicle Pool Replenishment in Cultured Cerebellar Granule Neurons using FM Dyes
Published on: November 11, 2011
Two endocytic recycling routes selectively fill two vesicle pools in frog motor nerve terminals
D A Richards1, C Guatimosim, W J Betz
1Department of Physiology and Biophysics, University of Colorado Medical School, Denver 80262, USA.
Abstract:
We have identified and characterized two vesicle recycling pathways in frog motor nerve terminals. We exploited the differential staining properties of FM dyes of varying hydrophobicity to label selectively two different vesicle pools, using optical imaging and electron microscopy of photoconverted dyes. During a 1 min tetanus, a rapidly recycling route places vesicles selectively into a small readily releasable pool comprising about 20% of vesicles. After the tetanus, a much slower pathway (from which FM2-10 but not FM1-43 can be rinsed) delivers vesicles via infoldings and cisternae selectively to a reserve pool with a halftime of about 8 min. Mixing between the two pools is slow. During stimulation at 30 Hz, 10-15 s is required to mobilize and release dye from the reserve pool.
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