Regenerative process after experimental injury of hypoglossal nerves in guinea pigs.

The nerve regenerative process has been investigated by many studies. However, the quantification of the degree of crush of peripheral nerves has not yet been performed. The aim of this study was to determine and standardize the ligature intensity and crush level of the hypoglossal nerve of guinea pigs. The compound action potentials evoked by electric stimulation were used as an index of the degree of nerve crush. To demonstrate nerve regeneration after ligating and crushing of the right hypoglossal nerve, fluorescein isothiocynate conjugated cholera toxin-B subunit (CTb-FITC) was injected into the intact fiber of the left hypoglossal nerve, and the central side from the crushed region of the right hypoglossal nerve fiber. The total cross sectional area of the retrograde-labeled hypoglossal motoneurons was investigated under a confocal laser scanning microscope. The results of the evaluation using CTb-FITC indicated that the nerve regeneration occurred from two weeks after crush and recovered in six weeks.