Quantitative studies on the mouse facial nerve trunk distal to the geniculate ganglion. An electron-microscopic study.
A fiber count analysis was performed with the electron microscope on the facial nerve trunk distal to the geniculate ganglion in seven mice. On an average, 4,836 (93%) of the total nerve fibers (5,201) were myelinated and 328 (6.3%) unmyelinated. The large part of the nerve consisted mostly of large myelinated fibers (large-fiber group). The small part of the nerve consisted of small myelinated and unmyelinated fibers (small-fiber group). The fiber constitution of the small-fiber group in the nerve was more like that in the intermediate nerve than that of the small-fiber group in the motor root of the facial nerve. Thus, it is postulated that the nerve fibers of the small-fiber group in the facial nerve trunk distal to the geniculate ganglion may be derived from the intermediate nerve, and that the nerve fibers of the small-fiber group in the motor root of facial nerve may course to the greater petrosal nerve.
D000818:Animals; D001369:Axons / Q000648:ultrastructure; D002452:Cell Count; D005154:Facial Nerve / Q000648:ultrastructure*; D005830:Geniculate Ganglion / Q000648:ultrastructure; D051379:Mice / Q000033:anatomy & histology*; D009413:Nerve Fibers, Myelinated / Q000648:ultrastructure