Figure 1. Cell wounding in the gingiva and tongue induced by brushing. (A) Confocal fluorescence image of epithelium and underlying connective tissue from the undisturbed (not brushed) maxillary gingiva. Epithelial cells labeled with the cell wound marker, fluorescein-labeled dextran, are not observed. (B) Confocal fluorescence image of epithelium and underlying connective tissue from the brushed, mandibular gingiva (taken 15 min after brushing). Epithelial cells labeled with fluorescein-labeled dextran are observed in all strata. (C) Confocal fluorescence image of epithelium and underlying connective tissue from the brushed mandibular gingiva (taken 3 hrs after brushing). Epithelial cells labeled with fluorescein-labeled dextran are observed in all strata. (D) Skeletal muscle of a tongue, which was not brushed. Fluorescein-labeled dextran is observed in the connective tissues surrounding the individual myocytes. The myocytes themselves are not labeled intracellularly with the fluorescein-labeled dextran. (E) Skeletal muscle of a tongue 15 min after brushing. Many of the myocytes display strong cytoplasm labeling with fluorescein-labeled dextran. (F) Skeletal muscle of a tongue 3 hrs after brushing. Again, many of the myocytes are strongly labeled with fluorescein-labeled dextran. (G) Quantitative analysis of fluorescein-labeled dextran labeling of epithelial cells. The average fluorescence intensity resulting from fluorescein-labeled dextran staining of cells was measured over randomly assigned domains of the epithelium of the undisturbed (not brushed) maxillary gingiva and brushed mandibular gingiva at two intervals after brushing, 15 min and 3 hrs. Significantly more fluorescence was measured at both time points in the brushed mandibular gingiva. Error bar = SEM; asterisk indicates a p value of < 0.001 (n = 3 animals, 5 sections each, 18–20 images each section), when paired with the undisturbed (not brushed) control, Mann-Whitney test. (H) Quantitative analysis of fluorescein-labeled dextran labeling of skeletal muscle cells. The average fluorescence intensity of individual myocytes was measured in undisturbed and brushed (15 min, 3 hrs) tongues. Error bar = SEM. Asterisk indicates a p value of < 0.001 (n = 3 animals, 5 sections each, 18–20 images each section) when paired with the undisturbed (not brushed) control, Mann-Whitney test. Magnification bar = 25 µm.