Fig. 4

Venogenesis was the primary angiogenic event in the infarct core. (A) The flow diagram provides a concise overview of the GIAO staining procedures. (B) ~ (C) Gelatin-ink infusion for normal and ischemic brains on day 14. Red arrow, inferior cerebral vein (ICV); black arrow, middle cerebral artery (MCA). (D) GIAO staining was performed to distinguish arterial and venous capillaries in the brain. The arterial capillaries presented blue walls and red lumens. Only red lumens were visible in venous capillaries. Black arrow and a., artery. Red arrow and v., vein. (E) GIAO staining of the infarcted brain on day 14 after ischemia. The majority of newborn microvessels in the infarct core were veins, as ALP staining was either absent or weak in the majority of newborn microvessels. (F) and (G) Gelatin-ink + ALP staining of the infarct core. The arterial capillaries presented blue walls and red lumens. Venous capillaries presented with red lumens. Black arrow and a., artery. Red arrow and v., vein. (H) and (I) GIAO staining of the infarcted brain on days 3 and 7. None or few gelatin-ink labelled microvessels were present in the infarct area on days 3 and 7. However, endothelial progenitor cells (arrowheads) significantly proliferated in the infarct core on day 7