A useful experimental model to study the pathophysiology of cerebral ischemia without craniectomy is the middle cerebral artery occlusion (MCAO) model. In this model, an intraluminal suture is advanced from the internal carotid artery to occlude the base of the MCA. Standardized procedures in terms of suture size, animal weight, and the details of intraluminal suture insertion are well established. This procedure can produce reversible occlusion after insertion of the intraluminal suture for a specified period of time, or a permanent occlusion by leaving the suture in place. This model has been useful in the study of both the normal pathophysiology of cerebral ischemia and in assessing interventional therapeutic approaches for stroke therapy. One approach has been the intravenous delivery of bone marrow-derived mescenchymal stem cells at various times after MCAO. Histological and magnetic resonance imaging have been used to quantify infarction volume in this model system.