Membrane currents in a developing parasympathetic ganglion.

It is reported that chick embryo ciliary ganglion neurons that have just terminated their migration and are in the process of forming a ganglion express several properties underlying membrane excitability. Evidence is presented which suggests that these cells possess voltage-dependent sodium, potassium, and calcium currents as well as a calcium-activated potassium current. These currents resemble those previously described in the more mature ciliary ganglion (Bader, C. R., Bertrand, D., and Kato, A. C. (1982). Dev. Biol. 94, 131-141) but may differ in their density per unit membrane surface. For example, the density per unit surface of the voltage dependent sodium current in younger neurons appears to be 5 to 10 times smaller than in more mature neurons.