Morphological study on the collaterals developed by one axon during peripheral nerve regeneration

Abstract

Outgrowth of collateral sprouts from axons is a natural process that arises during development of and regeneration in the peripheral nervous system. Our previous study showed that if there are enough distal endoneurial tubes into which the proximal regenerative axons can grow, one axon can support three to four collaterals, at most. Here, the proximal half tibial nerve was fixed to the distal stump and served as the donor nerve. The number of myelinated axons was calculated after 4 months. The ratio of distal regenerative myelinated axon number to proximal donor nerve axon number was 1.83 with the tibial function index and the nerve conduction velocities of - 48.6 ± 6.8 and 27.8 ± 5.3 m/s. The regenerated collaterals were isolated and observed to sprout from the node of Ranvier with almost the same features of normal fibers, but with different electrophysiological characteristics. This finding shows the evidence of one-axon trunk several-collateral model in peripheral nerve regeneration and suggests that such multi-collateral regeneration model may be useful in peripheral nerve reconstruction.

How many nerve fibres can be separated as donor from an integral nerve trunk when reconstructing a peripheral nerve trauma with amplification method by artificial biochitin conduit?

“…The CMAP of skeletal muscle is integrated by multiple single action potentials of nerve fibres under stimulation [7]. As a typical and mature method in the diagnosis of PNI [8], the maximal CMAP amplitudes quantify the complete structure of "axonmotor endplatemuscle fibre" and reflects the overall function of the motor units [9,10]. If the peripheral nerve is injured, the structural integrity will be lost due to axonotmesis with the decline of maximal CMAP amplitude [11,12].…”

Advance of Peripheral Nerve Injury Repair and Reconstruction

“…Moreover, mathematical relations have further been researched: an increasing ratio of distal stump axon numbers to proximal donor nerve axon numbers of 1.0, 1.83, 3.64, and 7.97 yielded ratios of regenerative myelinated axon numbers to proximal donor axon numbers of 0.98, 1.51, 2.39, and 2.89, respectively, estimating an approximate maximum value of 3.3 using the Hill function. [ 21 22 ] This phenomenon has also proved to exist in larger animal experiments,[ 7 ] where proximal regenerative axons can grow into distal endoneurial tubes by sprouting, indicating the reserved function of amplification and compensation.…”