Development of voltage-gated currents in newt retinal neuroblasts in culture

Neuroblasts dissociated from early regenerating newt retina (18-20 days after surgery) survived in culture and extended neurites. They were classified into three groups on the basis of neurite outgrowth patterns; monopolar, bipolar, and multipolar varieties. Freshly dissociated neuroblasts (3-15 h in culture) were characterized by slow-rising action potentials with long duration, mediated by inward Na+ currents. After a few days in culture, these cells produced much briefer action potentials mediated by the characteristic Na+, Ca2+ and K+ currents of ganglion cells dissociated from normal retina. The results suggest that neuroblasts in early regenerating retina differentiate in vitro into spiking cells, possibly ganglion cells, characterized by their morphology and voltage-dependent ionic currents.