synaptosome

[sĭ-năptə-sōm′]
n.
  1. A saclike structure containing synaptic vesicles and mitochondria, which breaks away from axon terminals when brain tissue is homogenized under controlled conditions.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.