Saltatory conduction and a novel type of excitable fenestra in shrimp myelinated nerve fibers.

The findings of saltatory conduction in the invertebrate giant nerve fibers were mentioned, and the experiments for analyzing the mechanism of impulse conduction in the giant myelinated nerve fibers of Penaeus orientalis and Penaeus japonicus were reviewed. Saltatory conduction was also found in many middle- and small-sized myelinated nerve fibers of, at least, 6 species of Penaeus shrimps. Saltatory conduction with its morphological basis in myelinated nerve fibers of vertebrates and invertebrates were compared, and it was concluded that the myelination of the nerve fibers in vertebrates and invertebrates has occurred independently.