The effects of minute direct electrical currents on cultured chick embryo trigeminal ganglia

The effects of low levels of electric current were determined on organ cultures of 6- to 19-day-old chick embryo trigeminal ganglia. Current levels ranged from 0·00115 to 11·5 nA/mm2; the time of electrical treatment varied from 2 h to 96 h. Low levels of electricity were found to have at least three major effects on this system of mixed cellular types: (1) Outgrowth of nerve fibers from the explant was enriched. This resulted in a greater number of fibers which were longer and more highly branched than those in control cultures. (2) Survival of neurons within the original explanted ganglion was enhanced by treatment with electricity. The presence of healthy neurons was found in 93·1 % of the treated culturesand in 53·5 % of untreated cultures. (3) Neurons, fibers and non-neural cells were stimulated to grow in the direction of the cathode. The rate of cathodal migration was calculated to be 0·1 mm/h (2·4 mm/day) in an explant from 12-day-old embryo. No differences were observed between surviving treated and control cultures in histochemical tests for acetycholinesterase. A similarity between the action of low levels of electrical current and nerve growth factor (NGF) is suggested.