Quantitative analyses
Results of the histochemical analyses were quantified in each zone of the SLIL and control tissues using the ImageJ software (version 1.53k, National Institute of Health, Bethesda, MD), as previously described (V. Carriel et al., 2014; Ortiz-Arrabal et al., 2021; Rodriguez-Pozo et al., 2020; Ruiz-López et al., 2022). In each image, we randomly selected five 25 µm × 25 µm square areas, and we obtained a numeric value (expressed as intensity units or I.U.) corresponding to the average pixel intensity within each square using the square tool of the software. Results were then subtracted from the blank values and averages and standard deviations were calculated for each group of samples. A total of 30 measurements were obtained for each type of tissue (controls and SLIL zones). Results corresponding to the analysis of cell phenotypes as determined by CD73 and S100 immunohistochemistry were quantified by determining the percentage of positive cells found at in each region of the SLIL. In short, we counted the total number of cells and the number of cells showing positive and negative signal within a 300 µm × 300 µm area randomly selected on each region, and the percentage of positive cells was calculated. The same method was used to quantify the number of blood vessels found at each SLIL region in samples subjected to CD34 immunohistochemistry.