Axonal conduction and electrical coupling in regenerating earthworm giant axons. 1992

A W Lyckman, and G D Bittner
Department of Zoology, University of Texas, Austin 78712.

Severed halves of medial giant axons (MGAs) and lateral giant axons (LGAs) in earthworms survive and are functionally reconnected as early as the first postoperative week. During the first 150 postoperative days, there is an increase in conduction velocity of action potentials and strength of electrotonic coupling between the severed axonal stumps across the lesion site. Electrophysiological analyses suggest that this functional reconnection occurs by transmission of action potentials through the lesion site by active propagation along neurites which make electrotonic connections rather than chemical synapses. The regenerated connections restore the original connectivity pattern for conduction of action potentials or spread of electrotonic potentials; i.e., MGA stumps reconnect with MGA stumps, and LGA stumps with LGA stumps. These and other data suggest that the mechanisms responsible for establishing appropriate functional reconnection of severed earthworm giant axons requires cell-specific matching of axons and neurites, rather than a competition between appropriate and inappropriate functional connections.

UI MeSH Term Description Entries
D008564 Membrane Potentials The voltage differences across a membrane. For cellular membranes they are computed by subtracting the voltage measured outside the membrane from the voltage measured inside the membrane. They result from differences of inside versus outside concentration of potassium, sodium, chloride, and other ions across cells' or ORGANELLES membranes. For excitable cells, the resting membrane potentials range between -30 and -100 millivolts. Physical, chemical, or electrical stimuli can make a membrane potential more negative (hyperpolarization), or less negative (depolarization). Resting Potentials,Transmembrane Potentials,Delta Psi,Resting Membrane Potential,Transmembrane Electrical Potential Difference,Transmembrane Potential Difference,Difference, Transmembrane Potential,Differences, Transmembrane Potential,Membrane Potential,Membrane Potential, Resting,Membrane Potentials, Resting,Potential Difference, Transmembrane,Potential Differences, Transmembrane,Potential, Membrane,Potential, Resting,Potential, Transmembrane,Potentials, Membrane,Potentials, Resting,Potentials, Transmembrane,Resting Membrane Potentials,Resting Potential,Transmembrane Potential,Transmembrane Potential Differences
D009412 Nerve Fibers Slender processes of NEURONS, including the AXONS and their glial envelopes (MYELIN SHEATH). Nerve fibers conduct nerve impulses to and from the CENTRAL NERVOUS SYSTEM. Cerebellar Mossy Fibers,Mossy Fibers, Cerebellar,Cerebellar Mossy Fiber,Mossy Fiber, Cerebellar,Nerve Fiber
D009416 Nerve Regeneration Renewal or physiological repair of damaged nerve tissue. Nerve Tissue Regeneration,Nervous Tissue Regeneration,Neural Tissue Regeneration,Nerve Tissue Regenerations,Nervous Tissue Regenerations,Neural Tissue Regenerations,Regeneration, Nerve,Regeneration, Nerve Tissue,Regeneration, Nervous Tissue,Regeneration, Neural Tissue,Tissue Regeneration, Nerve,Tissue Regeneration, Nervous,Tissue Regeneration, Neural
D009431 Neural Conduction The propagation of the NERVE IMPULSE along the nerve away from the site of an excitation stimulus. Nerve Conduction,Conduction, Nerve,Conduction, Neural,Conductions, Nerve,Conductions, Neural,Nerve Conductions,Neural Conductions
D009835 Oligochaeta A class of annelid worms with few setae per segment. It includes the earthworms such as Lumbricus and Eisenia. Earthworms,Eisenia foetida,Eisenia worm,Lumbricus,Lumbricus terrestris,Eisenia fetida,Earthworm,Eisenia fetidas,Eisenia foetidas,Eisenia worms,Lumbricus terrestri,Oligochaetas,fetida, Eisenia,foetidas, Eisenia,terrestris, Lumbricus,worm, Eisenia
D004558 Electric Stimulation Use of electric potential or currents to elicit biological responses. Stimulation, Electric,Electrical Stimulation,Electric Stimulations,Electrical Stimulations,Stimulation, Electrical,Stimulations, Electric,Stimulations, Electrical
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia
D001369 Axons Nerve fibers that are capable of rapidly conducting impulses away from the neuron cell body. Axon
D013997 Time Factors Elements of limited time intervals, contributing to particular results or situations. Time Series,Factor, Time,Time Factor

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