Epithelial Action Potentials in Embryos of the Australian Lungfish

The epithelial cells of the skin of embryonic Australian lungfish (Neoceratodus forsteri) between stages 30 and 39, are mechanosensitive and excitable, showing overshooting action potentials 400-800 ms long with a rapid rise followed by a slower repolarization (usually with a shoulder on the repolarizing phase), which propagate at around 10 mm s^-1. This skin impulse system is very similar to that found in embryonic and larval Amphibia; the significance of this similarity is discussed.