gap junction

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gap junction A communicating junction between cells, which provides a rapid passage for ions and small molecules such that they need not cross the bilipid layer of the opposed membranes. At the junction these membranes are only 2–3 nm apart, and within the intervening space there are arrays of closely packed cylinders, approximately 7 nm in diameter, each of which is pierced by a central channel. These junctions are a particular feature of cells that are in direct electrical coupling with one another (e.g. nerve and heart muscle cells, and perhaps embryonic cells).

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