Georgeu, G.A.; Walbeehm, E.T.; Tillett, R.; Afoke, A.; Brown, R.A. and Phillips, J.B
Nerve retraction: Contributions of peripheral nerve components and their response to tension.
Cell and Tissue Research, 320(2),
The mechanical architecture of rat sciatic nerve
has been described as a central core surrounded by a sheath,although the way in which these structures contribute to the overall mechanical properties of the nerve is unknown. We have studied the retraction responses of the core and sheath following transection, together with their tensile properties and the interface between them. Nerves were harvested and maintained at their in situ tension and then either transected entirely, through the sheath only, or through an exposed section of the core. The retraction of each component was measured within 5 min and again after 45 min. Post mortem loss of retraction was tested 0 min or 60 min after excision. For fresh nerves, immediate retraction was 12.68% (whole nerve), 5.35% (sheath) and 4% (core), with a total retraction of 15%, 7.21% and 5.26% respectively. For
stored nerves, immediate retraction was 5.33% (whole
nerve) and 5.87% (sheath), with an extension of 0.78% for
core, and a total retraction of 6.71% and 7.87% and an
extension of 1.74%, respectively. Tensile extension and
pullout force profiles were obtained for the sheath, the core and the interface between them. These showed a consistent hierarchy of break strengths that would, under increasing load, result in failure of the interface, then the core and finally the sheath. These data reflect the contributions of material tension and fluid swelling pressure to total retraction, and the involvement of an energy-dependent process that runs down rapidly post mortem. This study increases our understanding of the composite nature of peripheral nerve tissue architecture and quantifies the material properties of the distinct elements that contribute to overall mechanical function.
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