presynaptic dense projection

biology
Also known as: active zone

Learn about this topic in these articles:

nervous system

neuromuscular junction

  • striated muscle; human biceps muscle
    In muscle: Release of acetylcholine from the nerve terminal

    …the nerve terminal membrane called active zones. Freeze-fracture electron microscopy reveals an orderly array of small particles (about 10 nm in diameter) within these active zones, which are believed to represent voltage-gated calcium channels. The channels are opened by depolarization (an increase in membrane potential) of the nerve terminal membrane…

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