Objective To develop a technique that can directly demonstrate collateral sprouting of intact nerve fibers at endtoside neurorrhaphy site. Methods Five Wistar adult rats were used in this study. The common peroneal nerves at one side were sectioned at the level of knee joint, and their distal ends were sutured to the tibial nerves after removal of a 1 mm-diameter window in the epineurium. Three months after the operation, the nerve segments at neurorrhaphy site and the normal tibial nerves at the contralateral site were harvested. The specimens were fixed in 10% formaldehyde and postfixed in 1% osmium tetroxide, thenmacerated in glycerol. Single fiber was teased out in pure glycerol under an operative microscope, then transferred to a slide and observed under light microscope. The nerve segments at neurorrhaphy site and distal peroneal nerves were alsoharvested for histological evaluation. Results At the neurorrhaphy site, small nerve fibers sprouted from a donor nerve fiber near node’s of Ranvier. While such phenomena were not found in normal tibial nerve. From the longitudinal sectionof neurorrhaphy site, bundles of nerve fibers ranged from tibial nerve to peroneal nerve were observed. Lots of regenerative nerve fibers emerged in distal peroneal nerve. Conclusion The phenomena of collateral sprouting at end-to-side neurorrhaphy site can be demonstrated directly by nerve fiber micro-tease technique.
In order to observe the collateral sprouting capacity of the nerve trunk after end-to-side anastomosis, a window was made on the epineurim of the donor nerve through which the result of the end-to-end anastomosis of nerves could be compared. Sixteen SD rats were chosen and divided into 4 groups randomly. Group 1, the peroneal nerve was severed, the epineurium of the tibial nerve was fenestrated and sutured the peroneal stump with the tibial nerve by end-to-side neurorrhaphy. Group 2, operative procedures were almost the same as that of Group 1, but no fenestration on the epineurium was done. Group 3, the distal peroneal nerve stump was sutured in paralell with the tibial nerve without fenestration on the tibial nerve and Group 4, severed the peroneal nerve and sutured the stumps by end-to-end anastomosis immediately. The peroneal function index(PFI) and acetylcholine transferase (ChAT) activity were assessed and the histological examination was performed in all rats. The results showed: between group 1 and 2, there was no difference in PFI and ChAT activity (P gt; 0.05). The existence of collateral sprouting in all groups was proved by histological examination. Even in Group 3, there were plenty of nerve fibers turned into tiny myelined nerve fibers through collateral sprouting. But the ChAT activity in Group 1 was only two thirds of that in Group 4. It was suggested that the epineurial sheath did not influence the collateral sprouting of the nerve.