Cerebral ink perfusion. A. The dural blood vessels were parallel in the control group, there were few connections between the parallel blood vessels (100×). B. The dural blood vessels were parallel in the high-pressure groups 14 days after surgery, there were some connections between blood vessels and some enlarged veins (100×). C. The dural blood vessels were still parallel in the high-pressure groups 90 days after surgery, the blood-vessel enlargement was significant and the amount of connections between blood vessels increased significantly, and the diameters of the blood vessels for connection were relatively thin (100×). D. The artery was directly connected with the enlarged vein (200×).