Patterned regeneration of internal femoral structures in the cockroach, Periplaneta americana L.

The morphology of the nerve and tracheal supply to the extensor tibiae muscle in normal legs was compared to that in regenerate legs. In normal femurs, the extensor nerve and trachea extend along the posterior surface of the extensor muscle. The nerve and trachea are closely associated and branch coincidently at regular intervals.

Myelinated central vertebrate axon lacks voltage-sensitive potassium conductance.

Intracellular recordings were obtained from the goldfish Mauthner cell soma and axon before and after intracellular iontophoresis of drugs that block voltage-sensitive potassium conductance. Analysis of the action potentials generated by the axon hillock-initial segment and by the axon suggest that axonal impulses lack this potassium conductance. Thus, impulse repolarization in the Mauthner axon, and perhaps in other vertebrate central axons, may not involve an active potassium current.