PV-1 protein expression after ischemic insult. A. Top row, PV-1; bottom row, CD31; 100×. PV-1 is not detected 8 or 24 hours after ischemia, unlike the endothelial control marker, CD31. PV-1 expression is detectable in a small number of vessels in the affected tissue 48 hours after injury. PV-1 protein is expressed in a majority of the vessels and is comparable to CD31 staining levels in the injured region by 7 days after injury. Sham (uninjured brain) shows no expression of PV-1. B. Overview of PV-1 expression within the ischemic region 48 h and 7d after injury. PV-1 is induced throughout the affected brain tissue at 48 h (see arrows) and remains evenly distributed by 7d.