Gap junctions form in culture between chick embryo neurons and skeletal muscle myoblasts

Possible mechanisms by which neurons can affect the differentiated states of mononucleated cells in the early chick embryo leg skeletal myogenic lineage are being investigated. Under conditions of co-culture known to promote inductive interactions between embryonic neurons and leg cells, spinal cord neurons and mononucleated leg cells are coupled by gap junctions as shown by cell-to-cell passage of Lucifer yellow and hyperpolarizing or depolarizing currents. Co-cultures composed of ciliary ganglion neurons and clones of leg cells showed that the ability to form gap junctions with neurons is a differentiated function of myoblasts. Dye-coupling with neurons was found at high frequency only when the partner cell was a myoblast of a differentiating muscle clone. Myoblasts in undifferentiated clones formed gap junctions with each other but not with neurons. The nature of the junction-forming neuron is not restricted since neurons from spinal cord, ciliary ganglion and dorsal root ganglion all readily form junctions with myoblasts.