Quantitative research of the ultrastructure of regenerative nerve fibres affected by nerve growth factor or ciliary neurotrophic factor

Objective To discuss the effects of nerve growth factor (NGF) or ciliary neurotrophic factor (CNTF) on the ultrastructures of regenerative nerve fibles. Methods Thirty six Sprague-Dawley rats with 10 mm gap of sciatic nerve were randomly divided into two groups which had been bridged with the new double channel nerve conduit of fusiform shape (groups A and B, n=18 in each group). In group A, 200 μl chitin for medical use was injected into the conduit. In group B, the two branches of the conduit respectively contained 100 μl chitin and 5 μl NGF or CNTF. At 4, 8, and 16 weeks after operation, we evaluated the ultrastructures of regenerative nerve and analyzed the difference by counting method. Results There was not significant difference in the regenerative nerve fibres between the two channels in group A, but in group B, the number of myelinated fibre of regenerative nerves of NGF lateral branch was much more, and the myelin sheath was also thicker. Both the myelinated fibre and unmyelinated fibres in the CNTF lateral branch increased. The diameter of axon and the area of myelinated fibre of NGF lateral branch were larger than the ones of CNTF labteral branch, and there was significant difference between them, but its area of unmyelinated fibre was smaller than that of CNTF labteral branch. Conclusion NGF can significantly promote regeneration and myelinization of myelinated fibres. CNTF can promote the regeneration of both myelinated and unmyelinated fibres, but the ability of regeneration and myelinization of myelinated fibre is inferior to NGF.