Animals were deeply anesthetized with ketamine and submitted to neurophysiological evaluation by electromyography of the mandibular branch of the facial nerve aiming at obtaining find protocol compound muscle action potentials (CMAPs). Outcome variables were the CMAP amplitude and latency values. To obtain the CMAPs, we used a portable electromyography system (Neuro-MEP-Micro®, Neurosoft, Dhaka, Bangladesh) connected to a battery-operated Pavilion dv5C portable personal computer (Hewlett-Packard). The Neuro-MEP.NET software (version 2.4.23.0, Neurosoft) was employed to assess the CMAP data obtained under the following configuration of the electromyography

system: 10-Hz high-pass filter, 10-kHz low-pass filter, notch filter off, 60 mV of leading edge signal, and 10-kHz of sampling rate. The electromyography protocol has been established specifically for

evaluation of the rat facial nerve and described in detail by Salomone et al. (2012). Histomorphometric analyses were performed blindly six weeks after surgical procedure, and this method was well established by Costa et al., 2006, Costa et al., 2007 and Costa et al., 2012. After sacrifice, the surgically repaired portion of the facial nerve was cut into four parts, two distally and two proximally related to the graft. One pair of proximal (middle learn more of the autografting) and distal (3 mm distal to autografting) sections was fixed in 2% glutaraldehyde and 1% paraformaldehyde in 0.0031 M phosphate buffer, pH 7.3. After 60 min. in solution A, the tissue was postfixed for 2 h in 2% osmium tetroxide in phosphate buffer, dehydrated in ethanol, infiltrated

in propilene oxide and included in Epoxi® resin (Burlington, VT) until polymerization. Transversal, 1-μm sections were made and stained with 1% toluidine blue. Histological observations were carried out using light microscopy (Nikon Eclipse E 600, Nikon, Japan). The slides were photographed with a digital camera (Nikon Coolpix E 955, Nikon, Japan), and cell measurement taken (Sigma Scan Pro 5.0 software, SPSS Science). Qualitative analyses were performed according to general nerve architecture, pattern of tissue organization and myelination. For quantitative analyses of distal portion of the facial nerve, axons were counted in Bumetanide a partial area of 9.000 μm2 in three random microscopic fields for every fiber displaying its center within it. Total axon density was obtained by the ratio between total axon number and area. The shortest external diameter (including the myelin sheath) of all axons within a partial, randomly selected area (3.000 μm2) of the transversal section of the nerve was measured to evaluate the maturation of myelinated fibers (Mayhew and Sharma, 1984). The second pair of proximal and distal sections was fixed in 4% paraformaldehyde in phosphate-buffered saline.