Statistical analysis
Results obtained for each SLIL region subjected to each analytical technique were statistically compared with each control tissue. The two regions that we analyzed from each of the zones originally established by Berger were also compared (D1 vs. D2, M1 vs. M2 and P1 vs. P2). First, we evaluated the normality of each distribution using the Shapiro-Wilk test. As none of the distributions fulfilled the criteria of normality, comparison between two specific groups of samples were carried out using the non-parametric test of Mann-Whitney. The comparisons were done with Real Statistics Resource Pack software (Release 7.2) (Dr. Charles Zaiontz, Purdue University, West Lafayette, IN, USA), available atwww.real-statistics.com. A Bonferroni-adjusted statistical significance p value below 0.001 was set for all double-tailed tests, since multiple comparisons were carried out at the same time.