Defining gap junctions

In the 1960s there was adhesion and there was direct current transfer—a strange neuronal phenomenon whose mechanism was unknown. The two fields only gradually drifted together, but with the report by Revel and Karnovsky (1967) they were united around a distinct, structural correlate soon to be named the gap junction.

Eight years before, Furshpan and Potter (1959) had reported that subthreshold electrical stimulation (insufficient to elicit an action potential) still gave current transfer between some nerve cells. This apparently passive flow of current was seen in crayfish giant synapses and later in other cells. Robertson (1961) thought this phenomenon might be mediated by the membrane adhesions that he saw. In his words, “the elimination of the gap between the paired axon membranes…may conceivably be sufficient of itself to account for the apparently...