Specificity of junctional communication between animal cells.

Abstract

MANY types of animal cells, in culture and in vivo, form intercellular junctions which are freely permeable to small cellular ions and molecules but not to macromolecules1–10. These junctions are probably the gap junctions seen by electron microscopy11. Cells coupled by such junctions share their metabolites and small control molecules and respond jointly to changing demands on metabolism. Intercellular control of enzymic activity12,13 and metabolic interdependence causing controlled cell proliferation7 have both been observed in mixed cell populations in tissue culture. These integrative effects of junctional communication make a tissue behave as a homogenous unit rather than a collection of different cells.