Nerve Growth Factor: Optic and Ultrastructural Findings on Facial Nerve Degeneration in the Rabbit

After the discovery by Hamburger [3] and Levi-Montalcini [5] of the nerve growth factor (NGF), other neurotrophic factors such as brain-derived neurotrophic factor (BDNF) and cilliary neurotrophic factor (CNTR) [6] were found. At present we do not know whether a specific trophic factor exists that acts on motor fibers. On the other hand, the effect of the NGF on sensory fibers is known. Therefore, we used this factor locally on the transected area of a mixed nerve, such as the facial nerve, evaluating its possible action during the degeneration period.