Epidermal action potentials induce muscle excitation via the central nervous system in a newt embryo

A telobiotic chain of newt embryos was constructed from portions of two or three embryos. The posterior end of a normal St. 22 embryo (neural fold closure) was fused to the anterior end of a second, nerve-free St. 22 embryo, and cultured. After two days in culture, stimulation of the nerve-free portion produced a visible flexion response only in the normal portion of the chain. The percentage of flexion responses of the normal portion of the chain following tactile stimulation of the nerve-free portion parallels the decrement in sequential changes of the epidermal slow action potentials during normal development. Epidermal slow action potentials are conducted between two embryonic epidermal cells in all portions of the telobiotic chain. The authors have shown also that from stage 28-34, epidermal slow action potentials induced by intracellular depolarizing current evoke action potentials in the cervical spinal cord and myotomes.