Study Of Relative Problem On Topographic Specificity Of Facial Nerve Neurotropic Regeneration

Some kind of chemical materials was released by peripheral structure during theprocess of nerve regeneration, growth and development. The newborn axons were thenattracted to grow toward specific portions called neurotropism. It has been indicatedthat neurotropism including three specificity, tissue specificity, end-organ specificityand topographic specificity. So far, it is still an issue that whether topographicspecificity exits. The basic and mechanism of topographic specificity is unclear. Thefacial nerve is an important maxillofacial structure. However, there is no literature onstudy of facial nerve neurotropic regeneration after it injured. Based on neurotropism,all kinds of chamber were used to repair facial nerve gap. No report of manifoldr forsuch use was found. The nerve chamber can be made up of many kinds of materials.Chitosan was highlighted for its compatibility and degradable character. No chitosanmanifold was reported for restoration of facial nerve gap. This study would focus ontopographic specificity of the facial nerve neurotropic regeneration.Part â… . Comparative Anatomical Study of Extracranial Facial Nerve ofMonkeys, Pigs, Dogs and RabbitsAim: The aim of this study was to compare the anatomy of extracranial facialnerve in monkeys, miniature pigs, beagle dogs and New Zealand rabbits. Methods: Thefour kinds of animals were used in an anatomical study. The trunk and branches ofextracranial facial nerve were exposed and mapped. The diameter, length, pattern,myelin thickness, fiber density, number of branches and axons of facial nerve weredocumented. Result: Gross appearance of extracranial facial nerve of all four animalswas different from each other. Monkeys resemble human most, although they vary in pattern. Patterns of all the four kinds of animals are stable around2cm ranges, after thefacial nerve exiting from the stylomastoid foramen. The trunk of miniature pig facialnerve demonstrated the largest diameter. The trunk of beagle dog facial nervedemonstrated the highest number of axons. Conclusions: Patterns of monkeys,miniature pigs, beagle dogs and New Zealand rabbits are stable around2cm ranges,after the facial nerve exiting from the stylomastoid foramen. Monkeys resemble humanmost, while the other three animals are kind of different. The diameter andmicroanatomy of the four kinds of animals are similar, while the length of them variesgreatly. Variance of axon numbers in the four kinds of animals have nothing to do withits diameter of the facial nerve.Partâ…¡. Construction of chitosan manifoldAim: The aim of this study was to construct manifold with chitosan. Methods:The chitosan manifold was constructed by splicing or tooting. The tooting used formaking chitosan manifold was designed, and then improved. The procedure of makingchitosan manifold was explored. Result: The chitosan manifold can be made by bothsplicing and tooting. The tooting designed for making chitosan manifold can bemodified in branch number, diameter of branch and angle between branches, accordingto experimental demand. The procedure of making chitosan manifold was effective.Conclusions: Chitosan manifold made by tooting is much better by that was made bysplicing.Part â…¢. Model for topographic specificity of the facial nerve neurotropicregeneration research in rabbitsAim: The aim of this study was to create model for topographic specificity of thefacial nerve neurotropic regeneration research in rabbits. Methods: Six rabbits wereused in this study. The rabbit's facial nerve was explored and cut near the crotch,leaving a5mm gap. Then, the gap was repaired by chitosan manifold.1,2,3,8,16,24weeks later, ethology of the rabbit's face was evaluated. Result: The operation was successful. Five rabbits still alive,24weeks after operation. Swell or rejection was notfound. Conclusions: Model for topographic specificity of the facial nerve neurotropicregeneration research in rabbits was created successful.Part â…£. Spatial orientation of each branch in the extratemporal trunk of thefacial nerve by the neuroanatomical tracing methodExperiment1. Spatial orientation of each branch in the extratemporal trunk of therat facial nerve explored by Fluoro goldAim: This study aimed to locate the spatial orientation of each branch in theextratemporal trunk of the rat facial nerve. Methods: Fluoro-gold (FG) was applied as atracer in the neuroanatomical tracing method. Fifteen adult Sprague-Dawley albino ratswere randomized to five groups. FG was applied to one branch in each group. Facialnerve trunk was then cut at three points for fluorescence detection. Result: Each branchof the facial motor nerve has a topographical orientation in the distal part of ETFN. Thetemporal branch revealed an crescent shaped zone of axonal labeling in the medials andthe acroscopic aspect of the nerve. The zygomatic branch occupied a quarter in thelateral and acroscopic aspect. The buccal branch occupied the upper half. The marginalmandibular branch showed as an oval zone in the inferolateral half, and the cervicalbranch showed up as a square zone in the lateral aspect of the nerve. In the middle partof ETFN, the FG labeling zone dispersed to some extent, but the orientation was stillobvious. In the proximal region, all the branches rotated and the orientation becameblurred. Conclusions: In all, each branch of the facial motor nerve had a topographicalorientation in the distal and middle part of ETFN, but the branches rotated and diffusednear the stylomastoid foramen.Experiment2. Spatial orientation in the extratemporal trunk of the rat facialnerve explored by double labelling Aim: This study aimed to locate the spatial orientation of buccal and marginalmandibular branch in the rat facial nerve trunk near the stylomastoid foreman. Methods:FG and Fluoro ruby (FR) were applied as a tracer in the neuroanatomical tracingmethod. FG was applied to buccal branch and FR to marginal mandibular branch. Facialnerve trunk was then cut at the stylomastoid foreman for fluorescence detection,together with the brain stem. Result: The buccal branch and the marginal mandibularbranch occupied in the upper and lower half, respectively. The overlap area of bothbranches approach2/3of the whole section. No double labeled fiber or neuron wasfound. Conclusions: All the branches rotated and the orientation became blurred nearthe stylomastoid foramen.