Severed distal stumps of limb motor axons in the crayfish Procambarus clarkii remain ultrastructurally intact for at least 2-3 ms after being severed from their cell body. Initial regeneration of a motor axon is associated with the appearance of up to 200 small profiles (satellite axons) having no glial sheath adjacent to the large surviving stump for about 1 cm distal to the lesion at 4-5 wks postoperatively. These satellite axons are seen 2-4 cm distally at the target muscles 3-4 ms postoperatively. By 14-15 ms postoperative, the motor sheaths from the lesion site to the target muscles contain small axonal processes having thick glial sheaths. Behavioral tests show that some axons that are reconnected to the CNS at 4-5 wks may not be connected at 14-15 ms, whereas other axons not connected by 3-4 ms may be connected at 14-15 ms when the original distal stumps have degenerated. We suggest that all these data can best be explained by the view that motor axons in crayfish limbs initially regenerate via activation of the surviving distal stump by satellite axons which grow out from proximal stump. In most cases, these satellite axons continue to activate the surviving distal stump as they slowly grow to the target muscle. Eventually the satellite axons reform synapses on the target muscle and the original distal stump degenerates.
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Rev Med Liege
December 2024
Service de Dermatologie et Vénéréologie, CHU Liège, Belgique.
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December 2024
University of Pennsylvania, Philadelphia, Pennsylvania, USA.
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View Article and Find Full Text PDFNat Commun
November 2024
Centre for Cellular and Molecular Neurobiology, Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, OX1 3PT, UK.
Acta Biomater
January 2025
Department of Biomedical Engineering, College of Engineering, Virginia Commonwealth University, 601 West Main Street, Richmond, VA 23284, USA; Division of Hand Surgery, Department of Orthopaedic Surgery, Virginia Commonwealth University Health System, Richmond, VA 23298, USA. Electronic address:
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