For quantification of the images, five representative areas of each specimen were measured with respect to the integrated density of pixels using the ImageJ software (version 1.33u, National Institute of Health, Bethesda, MD). A mean value per animal was used to calculate the whole-group mean, and the averages of each group were analyzed and statistically compared. Polarizing microscopy The same groups, amounts of sample, procedures for fixing the specimens, and obtaining the frozen sections referred to above in the previous technique were used for polarization microscopy. After reaching room

temperature, the slides with longitudinal sections of regenerated nerves were mounted in distilled water Inhibitors,research,lifescience,medical and observed under the polarizing Inhibitors,research,lifescience,medical microscope (Olympus BX51-P BX2). Nerves are negative birefringence (ne > no) with respect to their long axis due to the acyl group of lipid staking perpendicular to the nerve axis, this mimic a smectic liquid crystal (Vidal et al. 1980; Vidal 2010). So, to detect nervous fiber and their orientation in sections it was used the rotating stage of the microscope to visualize the birefringence brilliance dependent on the relative angle of the nervous fibers to the crossed analyzer and polarizer. To study the myelin sheath the compensators according Senarmont 1/4λ and/or Braceköler 1/10λ were employed (Vidal et al. 1980). This microscope allows one to change the Inhibitors,research,lifescience,medical inclination angle of

the slide, and hence that of the tissue in relation to the analyzer and the polarizer. Depending on the angle of the slide, the desired birefringence compensation could be obtained, increasing or decreasing the brightness intensity of the collagen Inhibitors,research,lifescience,medical (−45°) or of the myelin sheath (+45°). The images captured were analyzed using the image analyzer Image-Pro Plus 6.3, Media Cybernetics, Inc. (Silver Spring,

MD). Statistical CP-690550 solubility dmso analysis The Inhibitors,research,lifescience,medical data are presented as the mean ± SEM and were analyzed using the one-way ANOVA followed by Bonferroni post hoc test, for multiple comparisons at P < 0.05 (*), P < 0.01 (**), and P < 0.001 (***). Results Characterization of the collagen with supramolecular organization Macroscopically, the implants were shaped in a prismatic form PD184352 (CI-1040) and showed a white coloration with a spongy aspect and soft texture (Fig. ​(Fig.1A).1A). The material proved to be hydrophilic in contact with saline, assuming the aspect of a gel without, however, dissociation. When observed under the polarization microscope, the collagen fibers were proven to be arranged parallel to each other with a high degree of alignment at the different depth levels (Fig. ​(Fig.1B).1B). This aspect was also seen under transmission electron microscopy (Fig. ​(Fig.1C).1C). A 3D electron tomography reconstruction video of the collagen implant is presented as Movie S1. Figure 1 Characterization of the collagen with supra-molecular organization. (A) Fragment of collagen used for a preimplant in vivo. Scale = 1 mm.