Microvascular morphometry in primate diaschisis

Focal cerebral ischemia was produced in monkeys by transorbital occlusion of the right middle cerebral artery. Following this, in one group of animals the total microvasculature, including both perfused and nonperfused vessels of the opposite caudate nucleus and insula, was examined by alkaline phosphatase staining of the endothelium. In another group, the patency of the microvascular bed was visualized by india ink perfusion. The number, diameter, and length of visualized vessels were measured by means of a Wild ASBA image analysis system. The perfused patient microvascular bed was significantly reduced in both insula and caudate nucleus in the supposedly normal left side, although the total microvascular volume showed an increase at 4 and 12 hr in the insula and at 48 hr in the caudate nucleus. Reduced perfusion in the hemisphere opposite to the occluded middle cerebral artery provides an anatomical substrate for the phenomenon of "diaschisis."