Functional Evaluation of Low Resistance Junctions: Influence of Cell Shape and Size

Specialized junctions, which allow small molecules to move directly between adjacent cells in many adult and embryonic tissues, may be involved in electrical or non-electrical forms of intercellular communication. The ability of the junctions to mediate either form of communication depends on the permeability of the junctions and on the shape, size, and arrangement of the interconnected cells. Electrical communication depends on junctional resistance and on non-junctional resistance which is a function of cell surface area. Non-electrical communication, it is argued, depends on junctional permeability to small molecules and on cell volume. The dual dependency of non-electrical communication in particular is discussed in detail and some of the possible implications are illustrated with specific examples.