Fig 4. Morphological analysis (hematoxylin and eosin + Indian ink staining specimens).
(A–C) Control group, (A) 7-week-old, (B) 6-month-old, (C) 1-year-old, (D–F) Gingival massage (MSG) group, (D) 7-week-old, (E) 6-month-old, (F) 1-year-old. Looped blood vessels were observed corresponding to the lamina propria under the outer epidermis of the gingival surface layer. In the control group, the height of the looped blood vessels (white arrowheads) reduced with age. There was interruption of blood flow in some blood vessels; hence, the ink was unable to enter these vessels (black arrowheads). Compared with the control group, most of the blood vessels in the MSG group maintained an ink-injected circulation (white arrowheads). The total area of blood vessels stained with ink within a certain range of images (200×200 μm) was increased in the MSG group compared to the control group for all three ages (A: 4177.0±1199.9, B: 2180.0±527.3, C: 1858.2±781.3, D: 5285.4±602.2, E: 3759.8±1592.0, and F: 3878.2±657.5 μm2, n = 3 in each group) (A: 4177.0±1199.9, B: 2180.0±527.3, C: 1858.2±781.3, D: 5285.4±602.2, E: 3759.8±1592.0, and F: 3878.2±657.5 μm2, n = 3 in each group). Regarding the one-year-old rats, there was a significantly higher amount of blood vessel staining with ink in the gingival massage group compared to the control group.