Fig. 4

Representative images of immunohistochemical stainings showing liver tissues stained with VEGF on day-0 (control) (a), − 1 (b), − 2 (c), − 3 (d), − 5 (e), − 7 (f), − 10 (g) and − 14 (h) (× 100) (scale bar, 100 μm). i–l Staining patterns of hepatocytes with VEGF, gradually progressing from the periportal area to the pericentral area. i Score 0, no staining (× 100) (scale bar, 100 μm). j Score 1, expression limited to periportal hepatocytes (× 200) (scale bar, 50 μm). k Score 2, VEGF expression in periportal and perisinusoidal hepatocytes (× 100) (scale bar, 100 μm). l Score 3, complete VEGF staining in all hepatocytes including pericentral areas (× 100) (scale bar, 100 μm). Blue arrows indicate VEGF positive hepatocytes. m Induction of angiogenesis after partial hepatectomy revealed by immunohistochemistry. The level of VEGF expression was evaluated based on a four-tiered scoring system on a scale ranging from 0 to 3 (as explained in the methods section [vide supra]). Immunohistochemical evaluations of VEGF expressions of liver tissues obtained from the rats demonstrated that highest angiogenesis activity was observed on days 1–3. VEGF expression gradually declined after 72 h and returned to its baseline value on day-5. n Induction of liver angiogenesis after partial hepatectomy. Vegf mRNA expression levels of liver tissues obtained from the rats demonstrated that highest angiogenesis activity was observed on day-14. Vegf expression gradually declined on days 1–3 and started to increase after day-3