ABSTRACT
The presence of direct intercellular communication via electrical signals was first demonstrated by E. J. Furshpan and D. D. Potter in the crayfish. The presumptive structure responsible for this electrical coupling, the gap junction, was first described by J. D. Robertson, also between giant axons in the crayfish. The presence of gap junctions between differentiating muscle cells has been reported in developing tadpoles, neonatal rats, and cultured myoblasts and their possible role in cell fusion was suggested. Most of the studies presently available report properties of gap junctions which are already present between different cell types, such as blastomeres, salivary gland cells, hepatocytes, cell lines, neurons, and cardiac and smooth muscle cells. The time course and the factors that may regulate electrical coupling formation were investigated using cultures of Xenopus myotomal muscle cells where the extent of coupling was monitored with intracellular microelectrodes.
